Ok, that code change was not in nuke -specific part but in generic city size reduction. Changing the logic there is risky at least. For one thing it's usually used at turn change time when city is in inconsistent state and updates should be queued and combined in general (not sent unconditionally). I'd say we need to send city update to everyone in nuke-specific part. Working on a patch...
Likely regression introduced by #41810.
"Yet it's a regression that other cities are not sent to their owners (they can be affected *at least* by fallout, maybe also by the worker rearrangements of the nuked city). We should send do both."