There is a little more context on this in b/268445629, cl/494699962 (sorry, Google only).

From a member of the Android team at Google:

Thanks for the bug report. This issue is fixed in Android U. Besides the spammy logs, this shouldn't be causing any issues.

A Google-internal Android framework also ignores this message. The message can become very spammy and concerning to users (see e.g. https://stackoverflow.com/questions/73432326/failed-to-find-sync-for-id-0-in-flutter), especially if it is covering up otehr problems.

/cc @reidbaker fyi, @christopherfujino - I'm pretty sure we have things in the android logging logic to ignore other messages already.