Twitter was able to change the logo of their iOS app but not the name, since Apple requires app names to be at least 2 characters.

They’re also still referring to the app as Twitter in the update notes (via
@sferik)

@taylorlorenz @sferik You can keep the old bird icon and name, with that little trick: https://hatchee.bz/@tomakoon/110790273922408160 - You know, just to annoy #ElonMusk a bit too.