I am usually less communicative, and get into a "super-deliver" mode. Trying to fix things by myself, and maybe not including others enough. My answers might be shorter than usual, and more dry.
I really try to be a team player - so if you see me "acting solo" that might be a sign of me trying to "rush things" to get things done.
If you have worked a bit with me you probably know that I'm positive, talkative and care for others. Under stress I lose some of that spark, shut up more (to try to get in "productive" mode fast), and lost some of the human touch.
You can always reach out to me and ask how I'm doing. I'm usually quite open about it - once I am confronted with the self-reflection that your question allows.
It might easily be that we just need to confront reality and inform that what we promised was not doable - and share what we tried to do.
The teams I have worked the best with have been the ones that once I was getting into a stressful mode, they would let me know and offer help.