Clicking yes on the quit match prompt does not do anything after a desync, forcing an alt-f4 to quit.
This is a known issue. People intentionally use a desync exploit to abruptly end the game. It actually causes two crashes: one from the game to the score screen. However, the game also can’t process any further after the score screen and it will just terminate the program, eventually.
The best way to fix this is to patch the exploit from occurring. Although I have not seen this yesterday I find it too early to state if this has received attention in the current patch. It is not mentioned in the notes but I can well imagine that this is done in the background.
Unfortunately this means that you and me as an individual can’t do much about this rather than waiting it out.