The custom rules (i.e. UniqueRule()) is not receiving the validated value from the previous rule validation of the same row (if there are any), instead it receive the original value.
Example:
$validated = $request->validate([
'title' => ['required', 'sanitize:text', new UniqueRule(Tag::class, 'title')],
]);
Here, the UniqueRule() does not receiving the sanitized text value although it has a rule "sanitize:text" before the UniqueRule().