I’m using plasma 6.5.4 and every time I restart my pc or wake up it from sleep mode, my cursor theme and start screen animation go back to default ones. I’ve been switching them back every time, but it doesn’t help.
Can’t say it’s your issue but on my roommates machine he had toggled on the “Switch To Dark Mode At Night” at the top of Colors & Themes under Appearance & Style in System Settings. Took me a couple of reboots before it dawned on me what might be happening.