HEIF/HEVC aren't completely open formats though, AFAIR. I'm pretty sure there's some kind of patent royalty involved in some things people might want to do with them.
That alone makes them incompatible with GNU's ideals, such as they are.
That's true, but that's an argument about the iPhone and not Photos. On the iPhone, there's literally a switch to instead save as jpg/h.264...which do have their own patent problems (there have been various successful patent collections on jpeg and h.264 is subject to the same MPEG LA group HEVC is).
