These two settings sometime change back to default (on) on startup of computer

This is not hardware specific as it happens across all my machines (intel, nvidia and amd)
in the screenshot i have turned them off. but it’s really annoying to have to change them every time it switches to default. (English is my first language, I’m just really bad at it…)

This is a known thing, for Kubuntu 25.10-26.04 upgraders, at least. This is being worked on, but a manual fix is pretty simple.

In addition to the explanations in the linked post (which also includes a script to fix values), you can also keep the effects enabled but just disable the transparency value and animation values inside the effect settings, so they actually don’t do anything, even when the effects are enabled: