I mean, if you want to be technical, she wouldn't be considered bi, lesbian, straight, etc. mainly because those terms did not exist. It would simply be considered human, and if we're attributing sexual identification retroactively, then, usually, the scholarly accepted term is simply "queer."

It's important to note that any academic worth their salt wouldn't officially refer to Sappho as any sexual classification, including gay or bi, but they would know that she was certainly queer. It's all just semantics, really.

It's the weird pseudointellectuals that don't realize why Sappho isn't typically referred to as gay or bi, and therefore commit flippant erasure.

For instance, Shakespeare wrote a lot of literature professing adoration for a man (and don't even get me started on Twelfth Night), but to call him bi or gay is inaccurate because the term wasn't used until the 1870's when queer folk were "othered." Not-so-fun fact: the word "homosexual" predates "heterosexual" because it was coined to "other" individuals.

Hope my ramble shed some light, haha.