After upgrading to Windows 10 20H2 and doing the 2020-10 culumative Update for 20H2 (Build 19042.572) there are still “event=rich_presence_failure” and “Trying to lock an invalid SNO” errors in the D3Debug file.
The problem with the old dll is definitely still present, however I did not experience any lag/freeze/stutter in the game so far (4h played).