No worries! It does but only at the weakest points, and these break points would be more easily broken down by any means (chemical/biological or thermal through radiation).

The issue is that the entire molecule isnt made up of these, and so anything UV would be able to do (at least in our atmosphere), biologically bactieria can’t do much better.

Its also part of the reason we can’t just toss our trash in a big ol UV light or just leave it out in the sun and expect it to disappear; all its useful properties will but the brittle plastic leftover won’t. This is why recycling plastic is so hard compared to other materials.