Not sure exactly how they report what, but i assume they leave it up to you to determine your own taxes for stuff like that
I think exchanges generally do chainalysis so that they can tell the government they kicked off all the criminals they found and stuff, so they can be compliant and continue operating - as opposed to nitpicking which individual transactions they think are taxable events on your behalf. That part is up to you
Please note that i am to some degree talking out of my ass here. Just my impression of things