When I'm under stress, I withdraw more, and get shorter with people. I generally need a lot of alone time but I take it to more of an extreme when stress is involved. I'll get overly focussed on little things that don't really matter, and repeat things in a loop in my mind.
I'll be less on top of things than I usually am, and lose track of time. I become significantly uncharacteristically forgetful, and loose focus of my interests and goals. There are times when my stress mode has been triggered and I've lost interest in a lot of things.
If it's due to a lot of stuff building up, I struggle to find motivation and get into procrastination mode. I still try to be polite, but people may notice I'm not quite myself. I have snapped at people under stress on occasion, but this is a very rare thing. I start seeing the worst in people, but my insecurities get louder. In private, I'll also cry when stress builds up.