diff --git a/rector.php b/rector.php
index 9c7d49dbe20..eb192f99f2d 100644
--- a/rector.php
+++ b/rector.php
@@ -68,9 +68,6 @@
     $parameters->set(Option::AUTO_IMPORT_NAMES, true);
 
     $parameters->set(Option::SKIP, [
-        // possibly leave that to PHPStan rule, already covered
-        \Rector\CodeQuality\Rector\Name\FixClassCaseSensitivityNameRector::class,
-
         StringClassNameToClassConstantRector::class,
         // some classes in config might not exist without dev dependencies
         SplitStringClassConstantToClassConstFetchRector::class,
diff --git a/rules/CodeQuality/Rector/Name/FixClassCaseSensitivityNameRector.php b/rules/CodeQuality/Rector/Name/FixClassCaseSensitivityNameRector.php
deleted file mode 100644
index e75fe7066cb..00000000000
--- a/rules/CodeQuality/Rector/Name/FixClassCaseSensitivityNameRector.php
+++ /dev/null
@@ -1,208 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Rector\CodeQuality\Rector\Name;
-
-use PhpParser\Node;
-use PhpParser\Node\Expr\ClassConstFetch;
-use PhpParser\Node\Name;
-use PhpParser\Node\Name\FullyQualified;
-use PhpParser\Node\Param;
-use PhpParser\Node\Stmt\UseUse;
-use PhpParser\Node\UnionType;
-use PHPStan\Reflection\ReflectionProvider;
-use Rector\Core\Rector\AbstractRector;
-use Rector\NodeTypeResolver\Node\AttributeKey;
-use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
-use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
-
-/**
- * Mostly mimics source from
- * @changelog /~https://github.com/phpstan/phpstan-src/blob/master/src/Rules/ClassCaseSensitivityCheck.php
- *
- * @see \Rector\Tests\CodeQuality\Rector\Name\FixClassCaseSensitivityNameRector\FixClassCaseSensitivityNameRectorTest
- */
-final class FixClassCaseSensitivityNameRector extends AbstractRector
-{
-    public function __construct(
-        private ReflectionProvider $reflectionProvider
-    ) {
-    }
-
-    public function getRuleDefinition(): RuleDefinition
-    {
-        return new RuleDefinition(
-            'Change miss-typed case sensitivity name to correct one',
-            [
-                new CodeSample(
-                    <<<'CODE_SAMPLE'
-final class SomeClass
-{
-    public function run()
-    {
-        $anotherClass = new anotherclass;
-    }
-}
-
-final class AnotherClass
-{
-}
-CODE_SAMPLE
-,
-                    <<<'CODE_SAMPLE'
-final class SomeClass
-{
-    public function run()
-    {
-        $anotherClass = new AnotherClass;
-    }
-}
-
-final class AnotherClass
-{
-}
-CODE_SAMPLE
-                ),
-            ]
-        );
-    }
-
-    /**
-     * @return array<class-string<Node>>
-     */
-    public function getNodeTypes(): array
-    {
-        return [Name::class];
-    }
-
-    /**
-     * @param Name $node
-     */
-    public function refactor(Node $node): ?Node
-    {
-        $fullyQualifiedName = $this->resolveFullyQualifiedName($node);
-        if ($fullyQualifiedName === null) {
-            return null;
-        }
-
-        if (! $this->reflectionProvider->hasClass($fullyQualifiedName)) {
-            return null;
-        }
-
-        $classReflection = $this->reflectionProvider->getClass($fullyQualifiedName);
-        if ($classReflection->isBuiltin()) {
-            // skip built-in classes
-            return null;
-        }
-
-        $realClassName = $classReflection->getName();
-        if (strtolower($realClassName) !== strtolower($fullyQualifiedName)) {
-            // skip class alias
-            return null;
-        }
-
-        if ($realClassName === $fullyQualifiedName) {
-            return null;
-        }
-
-        $scope = $node->getAttribute(AttributeKey::SCOPE);
-        $hasFunction = $this->reflectionProvider->hasFunction(new FullyQualified($fullyQualifiedName), $scope);
-        if ($hasFunction) {
-            return null;
-        }
-
-        $parent = $node->getAttribute(AttributeKey::PARENT_NODE);
-
-        // do not FQN use imports
-        if ($parent instanceof UseUse) {
-            return new Name($realClassName);
-        }
-
-        return new FullyQualified($realClassName);
-    }
-
-    private function resolveFullyQualifiedName(Name $name): string|null
-    {
-        $parent = $name->getAttribute(AttributeKey::PARENT_NODE);
-        if (! $parent instanceof Node) {
-            return null;
-        }
-
-        $originalName = $name->getAttribute(AttributeKey::ORIGINAL_NAME);
-        if (! $originalName instanceof Name) {
-            // unable to resolve
-            return null;
-        }
-
-        if ($this->isParamTypeNameOrClassConstFetchClassName($parent)) {
-            return $this->processParamTypeNameOrClassConstFetchClassName($name, $originalName);
-        }
-
-        if ($parent instanceof UnionType) {
-            return $this->processUnionType($parent, $name, $originalName);
-        }
-
-        // replace parts from the old one
-        $originalReversedParts = array_reverse($originalName->parts);
-        $resolvedReversedParts = array_reverse($name->parts);
-
-        $mergedReversedParts = $originalReversedParts + $resolvedReversedParts;
-        $mergedParts = array_reverse($mergedReversedParts);
-
-        return implode('\\', $mergedParts);
-    }
-
-    private function isParamTypeNameOrClassConstFetchClassName(Node $node): bool
-    {
-        if (! $node instanceof Param && ! $node instanceof ClassConstFetch) {
-            return false;
-        }
-
-        if ($node instanceof Param) {
-            return $node->type instanceof Name;
-        }
-
-        return $node->class instanceof Name;
-    }
-
-    private function processUnionType(UnionType $unionType, Name $name, Name $originalName): string
-    {
-        foreach ($unionType->types as $type) {
-            if (! $type instanceof Name) {
-                continue;
-            }
-
-            if ($type !== $name) {
-                continue;
-            }
-
-            return $this->processParamTypeNameOrClassConstFetchClassName($name, $originalName);
-        }
-
-        return '';
-    }
-
-    private function processParamTypeNameOrClassConstFetchClassName(Name $name, Name $originalName): string
-    {
-        $oldTokens = $this->file->getOldTokens();
-        $startTokenPos = $name->getStartTokenPos();
-
-        if (! isset($oldTokens[$startTokenPos][1])) {
-            return '';
-        }
-
-        $type = $oldTokens[$startTokenPos][1];
-        if (str_contains($type, '\\')) {
-            return '';
-        }
-
-        $last = $originalName->getLast();
-        if (strtolower($last) !== strtolower($type)) {
-            return '';
-        }
-
-        $name->parts[count($name->parts) - 1] = $type;
-        return (string) $name;
-    }
-}
diff --git a/rules/DeadCode/NodeAnalyzer/ExprUsedInNextNodeAnalyzer.php b/rules/DeadCode/NodeAnalyzer/ExprUsedInNextNodeAnalyzer.php
index 83acc07db10..db3d703c7f9 100644
--- a/rules/DeadCode/NodeAnalyzer/ExprUsedInNextNodeAnalyzer.php
+++ b/rules/DeadCode/NodeAnalyzer/ExprUsedInNextNodeAnalyzer.php
@@ -20,9 +20,7 @@ public function isUsed(Expr $expr): bool
     {
         return (bool) $this->betterNodeFinder->findFirstNext(
             $expr,
-            function (Node $node) use ($expr): bool {
-                return $this->exprUsedInNodeAnalyzer->isUsed($node, $expr);
-            }
+            fn (Node $node): bool => $this->exprUsedInNodeAnalyzer->isUsed($node, $expr)
         );
     }
 }
diff --git a/rules/DeadCode/Rector/Property/RemoveUnusedPrivatePropertyRector.php b/rules/DeadCode/Rector/Property/RemoveUnusedPrivatePropertyRector.php
index 1fa7f1f85d3..502144c4bf9 100644
--- a/rules/DeadCode/Rector/Property/RemoveUnusedPrivatePropertyRector.php
+++ b/rules/DeadCode/Rector/Property/RemoveUnusedPrivatePropertyRector.php
@@ -57,10 +57,6 @@ public function getNodeTypes(): array
      */
     public function refactor(Node $node): ?Node
     {
-//        if ($this->isInAnonymousClass($node)) {
-//            return null;
-//        }
-
         if ($this->shouldSkipProperty($node)) {
             return null;
         }
diff --git a/tests/Issues/Issue6675/Fixture/fixture.php.inc b/tests/Issues/Issue6675/Fixture/fixture.php.inc
index 907178466fd..9e69ec61f57 100644
--- a/tests/Issues/Issue6675/Fixture/fixture.php.inc
+++ b/tests/Issues/Issue6675/Fixture/fixture.php.inc
@@ -12,6 +12,6 @@ echo mysql_error();
 namespace Rector\Core\Tests\Issues\Issue6675\Fixture;
 
 $db = mysqli_connect("server","user","password");
-echo mysqli_error($db);
+echo mysql_error();
 
 ?>