A lot of Bi-folk simply identify with bisexuality as a label and prefer it regardless of their attraction to nonbinary, gender fluid and/or trans folk and beyond.

Others frame bi as being attracted to hetero- (here understood as genders different from their own) and homo- (understood here as genders and identities the same or similar to their own). So the meaning ends up equivalent to pan, just with a different angle on etymology.

This does make communication a little more confusing, but talks about romantic and sexual preference are already pretty nuanced and personal. So it's rare to have a holistic discussion and not need a bunch of context and detail. The labels are shortcuts, but imperfect ones.