Panic attacks before fights are probably more common than people realize.
During the walkout from Holly vs Ronda, you can CLEARLY see on camera Holly showing the telltale signs of a panic attack (my wife gets them)
Holly does her best "poker face" but you can see the uncontrollable muscle spasms that are kind of a signature "tell' of a panic attack. If I recall correctly her face twitched a bit in the cheeks and her abdomen was rapidly twitching, that's the giveaway, the muscle twitches tend to be rapid-fire in a way that would be nearly impossible to mimick if you try because it is your parasympathetic * nervous system which is misfiring to create the spasm.
(*I think, I mix these up)