Musescore 4

hi,i am a new musescore user
i downloaded musescore 4,and what do i lose if i switch to musescore 3

musescore 4 is full of unfixable and continiously repeated bugs
sometimes in a measure with the time signature of 4/4 has more than 4 beats
yes,you can do regroup rhythm/measure properties>measure duration but i have to do this for every bar
sometimes its completely unfixable and by using ctrl+del for just a few rests,the entire music gets cut in half
and if i do anymore from there it crashes
and i can't recover my music as the files are corrupted from the broken measures
sometimes ive spent hours on an arrangement all for this to happen,crash,corrupt.

if theres a fix for the mentioned issues(i have tried regrouping rhythms,changing measure duration and ctrl+del the extra rests)then pls tell me
otherwise what do i lose if i switch from 4 to 3