Plated vs. jacketed bullets for starters. 22LR is dirty in general. Cheap ammo even worse. But I shoot a pile of cheap ammo and don’t give a shit. Function stops before the accuracy does on my 10/22’s. Old bolt action head space gets goofy when it gets dirty and sends little dribblers.
I will clean an action but quit cleaning centerfire and rimfire barrels a long time ago. I stopped because they shot tighter without cleaning. On my centerfires, when the groups open up, it's time for a new barrel. Just my experience / opinion