iOS added fine-grained (at the contact level) access to contacts data last year.
https://lifehacker.com/tech/you-can-control-which-contacts-a...
Many apps have not updated and perhaps never will.
For example I know Slack still doesn’t use the single picture picker. They still want access to everything.
So iOS lets me limit what they can see, but it’s still a pain compared to just letting me pick the one picture I want.