I noticed that too, being a Firefox Linux user. I guess the developer either doesn't care or doesn't know. You can try to open an issue on his github page and see what he says.
I actually mentioned you in three different ways and some shows on some ui but not on another. Lemmy needs some basic standardization between instances.
The Photon dev replied in this post. Saying some sorcery that I don't understand. Idk if the problem is from our side or theirs.Maybe can you reply him?