Not really good news for the plastic that isnt waste. Plastic pipes or structures in buildings that were meant to last decades we dont want eaten away by fungus
Hate to break it to you, but if you store your food for years above freezing and without a protective atmosphere in a plastic container it's spoiled anyway.
For earth and the surviving creatures on it this is probably great news, but this is probably going to be a problem for humans in the short term. Plastic is this magic material that is immune to degradation and microbes, now that is no longer the case.
Ultimately that will be a good thing, but think about sanitized plastic medical equipment, now it can slowly be eaten up by microbes that we didn't have to worry about before.