Broken video output with KDE Plasma scaling

Hi! I have a small problem with broken UI. I know how to “fix” it, but I don’t think it’s a proper solution.

When I scale KDE Plasma to 1.5 and 144 DPI Shotcut is mostly aware of that. Majority of fonts are scaling properly, but video output is scaled down, and some fonts are pixelated. When I scale back to 1.0 and 144 DPI everything is back to normal, but some other apps are unreadable on my quite small screen.
I tried to add “export QT_AUTO_SCREEN_SCALE_FACTOR=0”, but program seems to ignore that (I’m adding it to command by “edit application” in Plasma).

I’m on 19.11.13
Intel Celeron 3350 with 4 GB of RAM (it’s fine for my work, thank you)
Souls OS 4.0
KDE Plasma 5.17.4

I also could not find that particular issue on that forum. There are some scaling posts, but none mentioned that one. Or I might be blind.

And I should also add, that I can live with that bug, it’s just annoying, but it doesn’t cripple my workflow, and it doesn’t really require much attention.