It’s not even June 12 for me, yet I suspect many subreddits went dark based on UTC.
I moved to Reddit during the Digg migration. Thus, I got the default subscriptions from back in the day. Over the years, I’ve unsubscribed to things I felt were crap, and I’ve added a number of subreddits.
Already, many have gone dark. My old.Reddit.com homepage already looks much different than normal, and I know that a few subreddits that do show have announced they’ll go dark. I assume they are US based and timing that locally.
I’ve spent more time in the Lemmy fediverse than on Reddit since joining, but I’ve spent time on both.
I’ll admit to cynical skepticism of the impact of the darkening. I still don’t think it will make a difference in Reddit policy, but I now believe it will have a larger impact on Reddit traffic than I imagined.
I still expect it to have no change in Reddit attitude or really in Reddit users.
If you want, you can also use a script like Power Delete Suite to overwrite all your old comments and posts with whatever copypasta you want, or to mass-delete (it does miss a few posts/comments though! be sure to double check), and/or you can use Redact to overwrite them with nonsense and then delete.
It used to be recommended to edit all comments at least 24 hours before deleting the account so that reddit would only have the edited, useless versions of the comments stored, but I don’t know if that works anymore, they might keep the pre-edited versions anyway now. I’m not sure.
Anyway, regardless, be aware that when you delete a reddit account they keep all your posts and comments, without the option to delete them after you account is deleted. If you want those deleted, you have to delete them first, then delete the account after. Also, if you want to use one of these deletion scripts, use it by June 30th, before the API change breaks them.