I’m not sure if 343i is aware, but…this is directed at multi-player specifically.
Offline customs have crashed more than once. Halo 2 Classic the worst notably for me.
Midship, Lockout, etc. most maps have crashed with 2+ people.
Crashes no more than 30 seconds in a match
Another was Halo 3
Halo 3 offline customs never seem to place anyone in teams, it always says “game over” with all players on one team;
A match seems only to work when playing FFA. Online, however, does work with teams.