1) I live in S. Korea, which is one of the supported countries.
2) I have access to Horizon worlds. I only have problems transporting to worlds labeled as 18+ because it says that I'm not old enough. This only became a problem earlier this year.
3) I'm in my 40s. I have my birthday properly registered online, on the headset, and on the meta horizon app.
4) I have contacted meta support about this issue more than once. They keep closing out my tickets as "resolved" after trying to get me to go through all of the same troubleshooting steps that I have done several times already, buck-passing it to other reps who try to walk me through all of the same steps again, then telling me I should just post about it online, lmao.
5) It could be a glitch, the meta support reps keep treating it like it is. But I can't get anyone to escalate it to the proper people or department. For a long time I thought it was an administration issue, but I don't know anymore. Fwiw, I've also submitted multiple dev reports on this issue, but nothing has been done about it, and it's been almost a year since I first noticed the problem.
Also bears repeating, I have access to 18+ worlds as long as the accounts are new and have only been loaded into those worlds under a VPN. But those accounts become "tainted" as soon as I try to load them into those worlds without a VPN because I can never load into them again after that, even with using a VPN. This happens across multiple headsets. I always get the same error message saying that I'm not old enough.