Probably a spicy take, but I feel like this wasn't actually a good "genderbender" manga. It's not a bad romance manga per se, but I feel like the actual genderbender element is a little lost, despite being the focal point. There's a vibe that it's not actually that important to the overall story, like you could've gotten more or less the same effect with the same emotional beats and same characters without any genderbender element at all. It also straddles this weird line of trying to be a grounded sci-fi thing, but doesn't really feel like it properly accounts for what a world with such a disease would actually be like and any of the actual effort to make it more than just magical genderswap kinda peters off as background set dressing.
Ultimately the gender related internal conflict doesn't feel that strong and the external conflict isn't really that fleshed out, so you're left with mostly just a romdram between a fairly normal hetero couple. Nothing wrong with that, but like it really didn't scratch the itch in terms of a story about gender.