Accessing a url with .local or 127.0 in the domain seems to be requesting this access. I have disabled setting such urls. This is just for the Testflight. Otherwise you can build the iOS/macOS client locally and allow for localhost access

Another area this can occur is in Search. I am still investigating why/how a request can push this modal through.

I have tested the API endpoint with local as a query since posts can either be federated, local or subscribed for instance, but that wasn't causing it.