There can be a lot of reasons why you’d want to block someone on Google Photos. For example, they might have said something nasty to you and now you want to cut them off from your life’s photos.
I can advise you on how to fix your relationships, but since you came here to learn how to block someone in Google Photos on iPhone/iPad, that’s what you’re gonna get:
Step 1: Open Google Photos app and go to Sharing tab where you’ll see all your shared albums
Step 2: Select the album that the person you want to block is a part of.
Step 3: Once inside the album, tap the three-dot menu from the top right corner
Step 4: Select Options
Step 5: Tap on the three-dot button next to the person you intend to block

Step 6: Select Block Person
Yeah, that’s it. The person’s blocked from viewing your photos now. Ye Happy?