macOS Tahoe introduced a new alert:

The alert is shown some time after the main app was closed. I am not sure what exactly triggers it.

Clicking "Do Not Allow" deactivates the background toggle in System settings. In macOS 15 and earlier, that toggle only affected login items. Now, this toggle seems to also affect the menu bar helper. It looks like macOS now automatically kills the menu bar app a short time after you quit the main app (if that toggle is turned off).

Curiously enough, PostgreSQL servers continue to run. The toggle seems to apply to the menu bar icon only. So macOS kills the menu bar helper, but leaves the "postgres" processes running.

We should probably explain somewhere in the docs how to enable background activities, so that people who accidentally clicked "Do Not Allow" can find out how to fix the issue.