You ask for "proof." I say it's self-evident. There's no point in continuing to trace this circle.
Yes I ask for evidence (not "proof") and yes you keep saying it is self-evident without giving any evidence of its existence. What is self-evident is that you have no evidence let alone proof (with or without quote marks).
If you poll a hundred thousand people who are familiar with BG3, I'm confident the vast majority of them would understand that BG3 is a big part of the Forgotten Realms setting now. That's how successful the game was.
However, there are always some folks who aren't capable of understanding for one reason or another. It doesn't bother me that you don't get it. I don't expect you to agree. I certainly don't expect you to understand things outside of your processing ability.