This looks worse than the issues I had, but have you been switching back and forth between Wayland and X11? That always gave me scaling issues.
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Plasma 6 Bugs
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I wouldn't say switching too much. I probably do it once every two weeks or so. Also, wouldn't reinstalling the system fix the whole thing? This happens on a fresh install out of the box. Wayland is just out of the question for me now, as I can never keep the 175% scaling.