You now once again remain flying after shifting between Creative and Spectator

youre supposed to still be flying when you switch in mid air. just not when standing on the ground

this is how it works in both 25w33a and 25w34a/b from what im seeing

the actual bug would be that if you switch to spectator and start flying, then switch back to creative, you lose the flying state

Yeah, I discovered that after I made this bug report.

This is not a bug. See the bug reports you mentioned