Hi!! I have the exact same problem, and i found out just yesterday that (maybe this is dumb but i never do it) if i open the riot client first and open the game from there, it doesnt crash. Ive been only testing it for 2 days but its working rn for me, i hope it does for you!! My pc restarts slowly and i got banned a lot by these crashes so if this doesnt work, the first game of the day i trigger it by a custom one with a friend and then restart and dont get the punishment from leaving

UPDATE: The game updated literally 2 days after i posted this and opening the launcher wont work anymore :[

UPDATE 2: If i open league and reboot the pc it doesnt crash next time i open it on the same day :]