Can one of the developers fix this?
in my experience that screenshot looks like private relay fighting your pi-hole dns. private relay wants its own path and if the phone is still shoved at pi-hole for dns it gets weird secure connection errors.
try flipping private relay off once, or set the iphone dns back to automatic while relay is on, and see if the warning goes away. not sure if thats exactly your case but thats what cleared it for me
I don't see how you are running Pi-hole so you'll need to chose the proper way to configure this, the default setting is to disable Private Relay because Pi-hole and Private Relay are mutually exclusive, you need to pick one or the other.
This is the config line that @nprampage referenced above, I'm including an image of what that config looks like at this time in case it changes in the future and a user coming to this topic doesn't know.