I know it's technically difficult, but still it's very important for trans and non-binary people to be able to change their username. For especially trans people it forces them to use their deadname or they are forced to make a new account. In either way they are forced.

Maybe if implemented, it should maybe be limited to e.g. 1x per 3 months. On the birdsite it's possible and it is one of the reasons people stay there.