Currently, additional workflow conditions cannot be used with Approval step as additional conditions will get ignored.

For example, let's say the following workflow condition gets added to additionally filter list of approvers:

This condition won't be evaluated against workflow transition and the button will still be visible for users who don't belong to the group.

This currently works as designed, but it would be beneficial to implement support for additional workflow condition so that the users can refine their approval steps and modify the process according to their needs.