It's worthwhile acknowledging that Reddit is increasingly controlled by bad actors, whether those are corporate advertisers, motivated political actors, or simply mentally unhinged individuals. I created s/UnrealTournament as a refuge from the mentally unbalanced (and likely bribed by Epic Games) mod team of r/UnrealTournament.
There are definitely facial recognition cameras that can identify you regardless of mask. I doubt the Met is using those currently, but it's no long term protection. Citizens need legal protections from intrusive spy tech, period.