Outdated by today's understanding of identity but this '90s show banged out many subversive pro-trans messages.
Ok, it was mentioned that she is a Trill with a symbiote that moves from host to host, BUT a couple relevant points.
1 - The worm (symbiote) that lives in them merges with the host, combining personalities. This symbiote has been joined to eight hosts at this point, which means there's about that meany people's lives in there.
2 - Not all trill get a symbiote, they typically go to a special academy and need to be in an elite group to get one. Once you merge, you can't unmerge without killing the host.
3 - this host, Ezri, was untrained and would not normally get a symbiote, but the previous host was killed and she was the closest available host, so she was assigned this symbiote without being properly prepared.
4 - two of the previous hosts - Curzon (a male host) and Jadzia (a female host) were extremely popular and well respected, which put a lot of extra pressure on the current host, leading to a lot of self doubt and personal identity confusion.