Eudae pills like mad. This is mostly caused by friction of any sort (in my experience). So I get this along the bum/back even with gentle washing because of friction vs. office chairs and such.
If you're in the states and have a top-loading washer, you're gonna have a bad time. Otherwise use wool/gentle cycle and hang dry - it won't completely avoid it, but it helps slow it.
There's "pill shavers" that can trim these off if they get too bad. e.g. - https://www.amazon.com/Conair-Fabric-Defuzzer-Battery-Operated/dp/B008I25368