It’s mostly “variant sudoku”, which are sudokus with all kinds of interesting and complicated rules. Rarely do they do a straight up sudoku anymore.
One of the two vloggers does the Sunday Times (of London) crossword, which is a puns-and-anagrams type of crossword. The other one does Heardle in a Minute.
Sometimes, they will solve other puzzles, like nurikabe, but it’s 90% variant sudoku.
I learned about the channel on this Board, in this thread: