One commenter on X, who said their partner was on the Delta flight, reported that it “smelled horrible” and that vanilla-scented disinfectant used to mask the odor “only made it smell like vanilla s---.”
Diverting is really expensive for the airlines, so you know they only do it if there is no other way. So it can't just have been a bit of a bad smell...
Some smells mask smell of shit better. There's even an old-school method of lighting and putting out the match after you did number 2: sulfur smoke kills the shittiness of ahit smell somehow