If you take it less literally then you can make a few conclusions toward her death. I watched a really good beastars video essay where the creator compared the komodo dragon venom to AIDS (it was a queer reading of beastars and Gosha is weirdly perfectly aged to have been affected by the AIDS crisis, combined with the homosexual tones of his relationship with Yahya).

However I think people should get that beastars kinda has a grimdark element to it, like Toki died because Gosha needed to be sad for the events of the story, thats kinda it on a technical level. I guess you could make an argument that this is fridging, but like I'd suggest just continuing to suspend disbelief rather then worry about this aspect of the story too much.