Hey, I just wanted to share my solution since steam refuses to implement this feature.

Filter out everything that does not include the offending tag, for instance I wanted to remove all FPS games from my steam deck collection because I play shooters on MKB, then when the collection is only FPS games I used the list to shift select all of the games remaining and removed them in a single action.

Then I removed the FPS tag from the dynamic filters and those games remained excluded while everything else returned.

It's stupid as ♥♥♥♥ that this is the best way to do it but at least it works.