Thanks, I knew about www.reddit, old.reddit, i.reddit, m.reddit, but I didn't know about this one. I can't find any info on it, what is the goal of sh.reddit UI exactly?

On another note, all kinds of interesting subdomains[0]. I wonder why a few subs get a subdomain?

[0] https://domain.glass/reddit.com

It's the new mobile UI, built on Web Components (via Lit), and it's much faster. Parts of it have apparently already migrated to the old experience.