So I began using tags recently but I guess I liked them so much that I've got around 30 of them now. Asking around it seems that there's no way to make Dolphin's places panel show tags dynamically (as in, "current folder only"), which would be useful for my usecase/workflow.
So I'd like to ask how/where to formally get this idea for the devs to consider.

Please file a wish on https://bugs.kde.org

I'm assuming I pick "wishlist" under the severity box for that, correct?

Exactly.