You're kinda pointing I think in the correct direction. There are different kind of facts. In this case the fact is a legal fact. One generated via the elector

You're kinda pointing I think in the correct direction. There are different kind of facts. In this case the fact is a legal fact. One generated via the electoral process and subject to rulings by the courts, and certification by the legislative branch. The electoral system and the courts have ruled universally that Trump lost. That system is made up of offices held by all the various factions. So the legal fact is Biden won the election. That's it. Saying otherwise is lying, saying it's debatable is also lying.