Everyone has “custom” pronouns. Some just match possible preconceived notions about them.
Specifically on she/they:
I use this on the internet sometimes because, when I give someone help on something technical, 90% of the time they thank an imaginary bloke. And if I correct them I’ll get trolls harassing me and patronising pricks giving me tips for beginners (including, often, the person whose question I answered).
When you don’t know, keep it neutral. Reinforcing stereotypes is harmful even if you mean no harm.
Interested I hearing about this. I try to be thoughtful and tactful about this choice when referring to folk but I wish I knew more about it to be improve about how to properly address folk.
Just use “they” by default (or the persons name) until you know what they prefer
I asked one person, they just said that she didn’t care. It’s annoying because I don’t know how to address him.
I’d default to they, and if they tell you to use something else, use it.
do birds fly? do ducks duck?
Are you Finnish by any chance?