Almost all my Google Photos "people" are mix-and-matched similar looking faces, so it's borderline useless. Immich isn't perfect, but it gives me the control to rerun face recognition and reassign faces when I want, even on my ancient GTX 1060.
Google photos isn't perfect either but I never saw these kind of issues when I was still using it.
Annoyingly you can't create a person that way yet with immich, but that's where digikam helps.