tl; dr
- Development builds of the Player contain the PlayerConnection class that allows remote debugging and other things across the local network. This is expected behaviour, and PlayerConnection is not used on release builds.
- https://issuetracker.unity3d.com/issues/ios-pop-up-message-would-like-to-find-and-connect-to-devices-on-your-local-network-appears-when-app-is-launched-on-ios-14
要は
少なくとも Development build
が有効だと出ます。無効にしても出る場合はサードパーティーのプラグインなどを疑ってみてください。