Big Fudge outer sleeves are damaging my vinyl jackets?

I have the 12 inch Big Fudge Polypropylene outer vinyl sleeves and I noticed that the outer jackets are getting damaged. It looks like the plastic is breaking down (?) and damaging the jackets similarly. I haven't even had them in these sleeves for very long! Maybe 6 months. I'm so sad:( Has anyone else had this happen? Any fix for it? Should I switch to a different brand/material of outer sleeve? I tried posting this in Taylor Swift vinyl and the vinyl sub and it just gets auto removed no matter what I do so I’ll try and post here. Just really hoping that someone can tell me why this is happening:(