PHP Warning: Declaration of Joomla\CMS\Toolbar\Button\SliderButton::fetchId($type, $name) should be compatible with Joomla\CMS\Toolbar\ToolbarButton::fetchId() in /Users/george/Sites/joomla-cms/libraries/src/Toolbar/Button/SliderButton.php on line 113
(found when running the stub generator as i don't see any uses of this in core). I think it wasn't properly migrated when doing #19670
This should fix all the issues (however I can't be sure because there aren't any uses of this in core)
Thanks