I have exactly the same problem,
An my host provider doesn’t is Godaddy, I’m hosted with knownhost. I have deleted theme twenty-twenty (via Filzeilla and cPanel) and it reinstalls itself. I also reinstalled the theme and now I have it duplicated: twenty-twenty and twenty-twenty_OLD.
PS
The twenty_twenty_OLD theme has three additional files to the original theme, and I think they have malicious code.
