You might do some improvement suggestions on the bug tracker, or even report some issue if you see serious regressions that don’t allow you to do certain things that were possible before.
You might find as well some information about the design changes, e.g. if they want a more uniform experience over different platforms etc. Sometimes they reach out to test new versions, that is a good point for feedback (e.g. Desktop Files Client 33.0.0 RC4 available).
That is strange, I thought the underlying code for syncing would be the same… but that is rather a different topic.