Built-in HDPI scaling leads to issues KDE Plasma Wayland

Bug Description

On Plasma Wayland on a HDPI screen, Mixxx automatically selected 125% scaling as default for me on first use, which I didn't notice at first. This lead to several issues:

1. Since my system-wide scaling setting was set to 125% as well, the entire UI was scaled too big and cut off on the right and bottom.
2. After I set my system-wide setting to 100%, the UI as a whole was scaled correctly, but tooltips were incorrectly positioned such that they would overlap the mouse cursor, therefore stopping it from hovering the element, therefore the tooltip would close immediately after opening

Only when I stumbled upon and set the application's HDPI setting to 100% (no scaling) did the tooltips work correctly. And setting the system-wide setting back to 125% produced a scaled UI that isn't cut off. In conclusion, on Plasma Wayland, the application should not try to guess a default for its internal HDPI scaling, but stick to no scaling and let the system do its thing.

Version

2.5.6

OS

Arch Linux - KDE Plasma 6.7.4