Abderrahim Kitouni commented on a discussion:
the last command should read flatpak install --reinstall flathub ${APP_ID} ${APP_ID} …
Once that's done, you should also delete the old remote flatpak remote-delete gnome, it will ask you if you want to remove some refs (all these refs should be Locale at this point). Answer yes, and then run flatpak update one last time, and you should be set.