Wrong. If the contract specifies a specific payment type and method and that is not adhered to it is a default. Try paying your morgage in rubbles and let me know how that works out.
Except Russia actually tried to pay in dollars, WITH THEIR OWN US DOLLARS, and the Biden regime illegally froze Russia's dollar holdings .
Try paying your mortgage if your bank freezes your account for political reasons. This is no default. This is political warfare.