I changed to iOS 26.5 and now the sign-in/sign-out option in App Store App is gone, or at least very well hidden. Appears you have to be signed in with the main Apple Account, so in effect can no longer be, on one device, in Settings Apple Account with one account, and in App Store with another account. Or sign out of App Store without signing out of Apple Account also.
If it is how it appears, then my technique of being normally signed out of both and hopping quickly into the App Store for the occasional App update, or to refresh contact such that the non-Apple apps resume working, will not work. Ah well.
And what’s worse is that as has been previously reported, if something in the alternate path breaks but isn’t discovered right away, then Apple won’t fix it, because now it is now a legacy bug.
That is, they will only fix bugs caused by Tahoe if they’re reported while Tahoe is the current macOS. If Tahoe breaks something but it doesn’t get reported until Golden Gate is released, now that bug is moved to the bottom of the priority list, because it is “not a regression”.
This is one of the reasons why moving to an annual major upgrade release cycle has caused such a deterioration in quality.
I’m glad I found this thread, so thanks for the hint. I use an old iPhone 12 as a music player, connected to my Pioneer amp with AirPlay, so the quality is amazing. I use a separate SSID for this network so the traffic is isolated and neither need to be on the WAN. This setup has worked flawlessly for years but this morning, after a few weeks away, I experienced exactly the same symptoms you described.
As you say, I now feel uncomfortable about what’s still being checked in the background, despite the devices being air-gapped
