Did Reddit start blocking its subdomain-to-subreddit URL scheme?

Any subreddit used to be available at subreddit.reddit.com —> Reddit.com/r/subreddit

I have no idea if it was an advertised or officially supported scheme. And I don’t know what the nature of the URL redirect/rewrite/forwarding was. It was handy for remembering. Now all those links seem to redirect to the main domain.

Old.reddit still works but could go soon if they’re reorganizing schemes/standards.

I actually used that subdomain structure years ago to allow users to select different subset styles for subreddits.