Scary white substance on Polyethylene Sleeves

Hi everyone, I have a concern for my record collection.

Back in 2020 I purchased Sleevecity’s budget 3.0 record sleeves which are made out of Polyethelyne, not PVC. Never had PVC. Today I noticed on many of the outside of the sleeves that there is this white residue that I can scrape off with my nail. Mostly along the edges of the sleeve where is stretched around the record, some in the middle too. It’s not on the record jacket itself or even on the inside of the sleeve, as far as I can tell. Records look fine too.

Has anyone experienced this with these sleeves and what is it?