I got a thin raincoat, a thing I can roll and pack in my bag, I have been carrying it around for the last 10 years or so.

I think it was advertised as very water proof, like water would pearl on it.

It's probably full of PFAS, no idea if it has been leeching PFAS, but I know it's not very waterproof anymore, so that might be a worrying clue.