I think this creates a terrible UX. I have accidentally/unknowingly lost an hour or two of changes by closing/resetting the compose without accepting all. There needs to be some modal or warning that you are going to lose all of the compose changes. After a longer compose session, there are sometimes changes I want to keep but the compose session starts failing/getting wonky so I want a fresh start. If I forget to ‘accept all’ then I lose everything.
This is confusing UX and I think saving changes should not be undone unless we very explicitly tell cursor to UNDO all with a very explicit warning that you are going to lose changes.