This was occurring for me also since 9/20. I deleted all cookies on chatgpt, reloaded the site, and logged back in. It would work for 20 to 30 minutes then do it again. Each time, the browser console would have a ton of 503 errors.
It seems that some of their nodes are working and some are in failure state. Their load balancer is occasionally directing to failed nodes.
I had one done recently due to breaking a filling while eating a Jolly Rancher. The whole thing took maybe 2 hours.
The shot of novocaine to numb my jaw was the only pain, and even that wasn’t bad because the dentist used topical numbing before that. It was no different than getting a cavity filled.
My dentist has a cnc machine (CEREC) in the office to make the crown, so I didn’t need a temporary cap. Waiting for that to be milled was the longest part.
I had a bruise on my gums for a couple days from the shot and the retainer clamp, but it wasn’t even bad enough to stop me from eating.