This is why I hate rapid/classical.
@Zirpatek No mod here; but I can tell you:
Not much.
This is only enforced if a user has a real problem doing this very, very frequently.
Otherwise, innocents would pay the price; as sometimes life happens and one has to simply quickly walk away from a game; or what not.
I recommend just starting a new game when this happens to you; ofc keep the other one open & just go to lobby in a new tab and start a new one. As long as its not currently your move you can start another game at the same time.
Your other game's tab will flash if or when the other player makes a move; and if you have notifications on a pop up will appear by your clock (bottom right by default)