MIDI - Output (to KWAI ES-920)

After the update from Musescore 3 to Musescore 4 the MIDI output to my Piano didn't no longer work like it did in Musescore 3 still a few minutes before the update.
This happened obviously to other users of Musescore 4, as well.
Thus I regret the update to MuSc 4 and want "my good old" MuSc 3 back.
Dear Support-team,
what can I do to fix that problem? Or when will you release a bug-fix to all users experiencing the same problem?
Greetings from Germany
P.B.