I actually find large groups distracting and disorienting to the point that I have a hard time decoding conversations and that extra churn is what exhausts me in the first place. Also, trying to keep the mask on is also a bit exhausting so the moment I tell everyone that Im introverted and no longer have to pretend Im not things start to improve a bit.

Having said that, I think you have a point with the threat perception part. I do enjoy social contexts where I feel like I fit in and can be myself. The problem seems to be more with social contexts I am obligated to participate in, where I have to put on a mask of interest; probably the threat is to be found that you’re really not interested into that interaction.