It totally happens to me too, particularly during planks or upper body exercise, and certain yoga poses too. I think it’s your muscles starting to fatigue, though I know it doesn’t necessarily feel that way.
I think once you build up enough strength in that position though it should go away!! But I’ll bet if you keep pushing yourself to do more and more it’ll come back
Hmm, already seeing some classism rear it’s ugly head. Gonna keep an eye on this post to see how mask-off people go with that