It contaminates compost if you put PLA into a regular composter. It requires a special industrial compost facility to handle it and most aren't.
So it's trash.
If you put PLA in the recycling bin it is making sorting even worse because if you get a bit of PLA mixed in with your other plastic it's not going to be good. So it's definitely not even slightly recyclable.
So it's trash.
PLA is trash. Unless you have an industrial composter. It's horrible.
It also seems PLA doesn't degrade in landfills. It requires a built to purpose composting facility.