Well, that’s an interesting statement, considering it’s wrong.
MB1, the original: No specifications that all mugs must be F2E and F2U. Mugging Blitz Round 1
MB8, same story. Mugging Blitz Round 8
MB11, the most recent one, same story. Mugging Blitz Round 11 -2021's First-
So, no, that’s not clear at all. They’re definitely assumed F2U, but nowhere is it stated they’re F2E.
In any case, you seem to have otherwise agreed with what I said.