When are Mail fetch / push / manual settings aignored?

On an iPad and iPhone on version 14 of the OS I have:

Settings | Mail | Accounts | Fetch New Data off

Settings | Mail | Accounts | Fetch New Data | Manual for each account

Settings | Mail | Accounts | Fetch New Data | Push off

Settings | Mail | Accounts | Fetch New Data | Fetch | Manually

Although I had imagined that this would turn off all non-manual retrieval of email, it turns out that connecting to power overrides the settings above on both devices. There are claims such as https://discussions.apple.com/thread/251812167 https://discussions.apple.com/thread/250552561that that this behavior is a feature not a bug, and further (in the second link) that force-closing also overrides all these settings.

Is there some apple document that lists all the circumstances in these Mail settings are violated?