UI scale - wtf is going on?

So I unwisely updated addons after the Unhalted fallout happened, to start looking for replacement unitframes.

Now I’m stuck in a perpetual limbo where the UI scale thinks it has changed, and simultaneously thinks it has not.
-Log in, everything is tiny.
-Go into graphics settings, enable using UI scale.
-Everything is huge and overlapping, even at the minimum of 65% it’s too big.
-Disable UI scale, now it’s perfect… temporarily.

Logoff resets everything back to step 1.

It’s not any single addon either, everything is screwed up and mis-sized including the default playerframe. Trying now to find what settings file is even responsible for that, to either wipe it out or revert to an old copy but config-cache is the most sensible place and it’s not in there.

Nevermind, fixed it by blanket disabling UUF & BCDM.
I knew there was some fuss over display scale that caused their discord to blow up & developer quit, but didn’t think it was actively interfering with that setting.