Competitive Mode may require you to use the Steam Mobile Authenticator

+optional bool two_factor_enabled = 22 [default = false];

+optional bool two_factor_enabled = 11 [default = false];

+CTFGCClientSystem::BIsTwoFactorEnabled()

+two_factor_enabled

from https://github.com/SteamDatabase/GameTracking/commit/8764daaf43d493333b744fd77d24803727c89f6c