Why did Windows 11 just kick me out of my own local folder?

I am using Windows 11 Pro 23H2 22631.5472 and I lost access to a folder that I just created in Windows.

If I click continue I see this.

The security tab has a super suspicious NULL SID.

Anyway, if I try to add permissions to everyone, or even my user, I get this:

And then ultimately this: