Bug: Stems too long when line distance increased on staffs with less than five lines.
A couple of years ago (https://musescore.org/en/node/208931), I reported an issue of stem lengths being too long when the line distance is increased on staffs with fewer than five lines in Musescore 2. The same issue exists in Musescore 3.
The middle staff shows what happens when the line distance is increased from 1sp to 2.25sp. Musescore assumes that every staff has the standard five lines and so it over compensates the note length when staffs have less. In this case, the stem lengths are twice the size of the stems on staffs with unaltered line distance (e.g., first and last staffs).
In the original post, I suggest a couple possible solutions: add an option in staff properties to maintain the orginal note stem length when adjusting line spacing (i.e., unlock the two); and/or have Musescore calculate the increase in note-stem length based on how many actual lines are in the selected staff. "