Spurious CC2 events in MIDI out
When playing a score via MIDI out, MuseScore sends many CC2 (Breath MSB) messages between the Note-On/Offs. Typically, all the messages send the same value (60), so there's no need for this even if the event were necessary - but it is not, in most cases.
For an example, see the attached "Yesterday" score: Play it via MIDI out into some MIDI-recording software, then those CC2 will turn up. I have added a zip file of logs for the various MIDI channels that show these events, recorded with ReaControlMIDI in Reaper.
Edit: It seems these CC2s also occur in MIDI exports. See attached "Drehorgeltest" files.