Have you tried it like this? Identify people and pets in photos on iPhone - Apple Support
"Fix misidentifications
- Open the Photos app
on your iPhone. - Tap Albums, tap People & Pets, then tap the person or pet that’s misidentified.
- Tap Select, then tap Show Faces.
- Tap the image or images that are misidentified, tap
, then tap This is Not [name] or These are Not [name].
You can also fix misidentifications while viewing a photo in your library. Tap
or swipe up to see the photo information. Tap the misidentified person or pet in the bottom-left corner of the photo, then tap This is Not [name]."
You could also try to the third command in the menu with the three dots in the upper right corner of the album in the person to confirm the named faces and to remove the wrong ones.