This thread for example - the oyster mushrooms break down the plastic polymers into smaller polymers, but you don't necessarily want to be eating those either. There's also the added complexity of there being many types of plastic, with many types of additives, and unless your waste plastic is single-source it is difficult to know exactly what is being released into your mushrooms when they're working on the plastic.
https://www.reddit.com/r/mycology/comments/10wboly/blue_oyst...