I stumbled over this a few times, mostly when cleaning up older code. This basically just means that using the ?. member access no longer dictates what is possible on the right side.

Property reads were fine before (returning null if a part of the chain was null), method invocations were fine (either returning null or just being a no-op if a part of the chain was null). But assignments were not, despite syntactically every ?. being basically an if statement, preventing the right side from executing if the left side is null (yes, that includes side-effects from nested expressions, like arguments to invocations).

So this is not exactly a new feature, it just removes a gotcha from an old one and ensures we can use ?. in more places where it previously may have been useful, but could not be used legally due to syntax reasons.