The "Sync with address book" toggle under Content & Senders was off until
the user turned it on, so senders trusted on the phone stayed in the
local allow-list and never reached the "Trusted Senders" address book the
other devices read. A setting the user never chose now counts as on;
only an explicit opt-out, or a server without contacts, turns it off.
Linus Rath
86e33b9afe