When using getAttributes() with specific attribute class and flags, flag 0 will return just matching attributes with specified class, and 2 will return matching attributes with specified class and children of that class:
<?php
#[Attribute(\Attribute::TARGET_CLASS)]
class SomeAttribute {}
#[Attribute(\Attribute::TARGET_CLASS)]
class ChildAttribute extends SomeAttribute {}
#[SomeAttribute]
#[SomeChildAttribute]
class SomeClass {}
$rc = new ReflectionClass(SomeClass::class);
$r_atts = $rc->getAttributes(SomeAttribute::class, 0); echo json_encode(array_map(fn(ReflectionAttribute $r_att) => $r_att->getName(), $r_atts)), PHP_EOL;
$r_atts = $rc->getAttributes(SomeAttribute::class, 2); echo json_encode(array_map(fn(ReflectionAttribute $r_att) => $r_att->getName(), $r_atts)), PHP_EOL;
?>
output:
["SomeAttribute"]
["SomeAttribute","ChildAttribute"]