I have two screens on top of each other: Screen 1is on the bottom, screen 2 is on top. Screen 2 is larger than screen 1. I want Yakuake to always open on screen 1, which worked on Plasma 5. Since the upgrade to Plasma 6 (I'm running an X11 session at the moment), Yakuake will sometimes open correctly on screen 1, sometimes in the middle of screen 2 with a size appropriate for screen 1, and sometimes on top of screen 2 with a size appropriate for screen 2. I also have the feeling that once it opens on top of screen 2 with the appropriate size, it always stays on screen 2. Also, since the upgrade the tab bar and title bar buttons are way too large.
setting QT_SCALE_FACTOR_ROUNDING_POLICY=round appears to fix the issue