One thing I am surprised that so many do not know, is that PCV plastic sleeves damage vinyl records. There is some sort of chemical reaction with pvc to pvc, and for example my AUBE LP+7" on Praxis Dr Bearmann is ruined. So was GOAT/TEF split 7" on... dada drumming. I just noticed friend had Con-Dom "color of mans skin" on its PVC sleeves, and there was large areas already turning "matte".
Some sort of chemical reaction also happens with xerox covers and insert inside PVC sleeves. I just had couple 2nd hand 7"s stored for couple decades in thick pvc sleeves, and despite thick cardboard covers, both vinyl and the xerox inserts all ruined...
I recommend to simply discarding all those shitty thick pvc sleeves. I don't know why they still keep making and using them. Many times when you hear people complain how shitty old pic LP's sound like, well... it can be partly due being packaged in pvc sleeves which will add that nasty hissing sound on top of vinyl. There is no way cleaning it anymore.