If you die while you're in spectator mode (/kill or the void) and your previous gamemode was survival or adventure, and you then use F3 + N to cycle between spectator mode and your previous gamemode you always cycle to creative mode, instead of survival/ adventure mode.

How to reproduce:

1. Go into survival/ adventure mode
2. Press F3 + N to cycle to spectator mode
3. use /kill
4. Respawn
5. Press F3 + N again