Are banter blitz players who draw arrows on the board during the game breaking the FIDE Laws of Chess? According to the FIDE Laws of Chess:


  11.3.1 During play the players are forbidden to use any notes, sources of information or advice, or analyse any game on another chessboard.


Streamers and banter blitz players often draw lines and arrows on the board while discussing what moves they are thinking about. Here is Eric Rosen doing exactly that.

Surely this is every bit against the rules as using an engine?

If Wesley So can be defaulted for basically writing notes saying things like "Must try harder" why is this allowed?
I agree that it would break the FIDE rules against note taking, but this is not a FIDE tournament; it is online blitz on Lichess, so FIDE rules need not apply. You'd have to look at the Lichess terms of service instead. They say


  
  Cheating. We define this as using any external assistance to strengthen your knowledge and, or, calculation ability to gain an unfair advantage over your opponent. Some examples would include computer engine assistance, opening books (except for correspondence games), endgame tablebases, and asking another player for help, although these aren’t the only things we would consider cheating.
  


The definition is open-ended so it's really up to the Lichess administrators to interpret. Does drawing an arrow on the board during a blitz game "strengthen your calculation ability?". Perhaps, but one could also argue that it makes you waste precious time, so it is probably more of a handicap than anything else. More importantly, just the fact that the Lichess user interface supports drawing arrows during a game (something which I had never noticed, despite being a frequent user!) may reasonably be interpreted as implying that the administrators approve of that use.

I don't think the "banterers" who stream their games draw arrows as a calculation aid, but rather to communicate their ideas to their audience. I'd love to hear from anyone who uses this feature and finds it helpful while playing blitz for non-streaming purposes. (Arrows might be more useful for correspondence chess, but there you are definitely allowed to use analysis boards, opening books, notes, etc., so arrows shouldn't be a problem.)