play demo; play offline; failed to validate username

I'll tell this story in chronological order. I get a text from my friend yesterday to let him back into the realm. He sends a screenshot of Minecraft saying "Failed to verify username!" on the realm loading screen. So I try to get onto the realm (which I own), and it gives me the same message. I do a little research on how to fix this, and I conclude that I simply have to log out and back into the launcher. I do so, and then the launcher breaks. It would switch every second from "play demo" to "play offline", giving me a couple of error messages and telling me I had to buy the game again.

This went on for a while as I did more research, and I concluded that I had to reinstall the launcher. I do so, and nothing changes. After a little more digging, I end up signing into the same Microsoft account as my Minecraft one on the Microsoft store, and the Xbox app. I even went as far as uninstalling the launcher for Windows 10/11 and downloading the one for Windows 7/8. Through rigorous trial and error, I would occasionally be able to log into Minecraft normally, but when I tried to connect to the realm, it would present me the same "Failed to verify username!" message. Also, I can't log into Minecraft.net! I press the log-in with Microsoft button, and I enter my information, and it just brings me back to the login screen. 

I pretty much end up running around in circles until midnight! But in all seriousness, what is going on? What's weird to me is that when I was researching the "Failed to verify username!" message, all that came up was help for servers, not realms. What's more, my friend has the same issue with the realm, so I'm not sure what to think of that. Will he have the same trouble with his launcher?

PS- I've looked through this website too, nothing has worked yet.