https://www.reddit.com/settings/data-request
They must oblige within a certain time frame — even if your account has been suspended and I believe even if you’ve deleted your account. Curiously, this might be one effective way to protest. Golly I wonder what would happen if many people requested such reports simultaneously. It seems these must be processed manually by admins.
As a bonus, it’s nice because all your comments and messages are searchable.
In terms of protesting this is right up there with all the other “stupidly dumb and clearly going to be ineffective” ones that people tried.