Cilivization 6 PS4: What is a red circular icon next to city name?

I have spent hours trying to find the meaning of this red-ish circular icon on the city name. Can someone enlighten me please?

I have conquered a city and it has been like this for over 10 turns. The city is not growing despite having food, amenities and housing. There is nothing useful shown in the city details screen either.

It indicates that the city is currently occupied:

Occupied cities

[..] are fully functional from the start (i.e. do not go through a "Resistance" period); however, their productivity is severely limited:

• First, they simply won't grow in Population, even when all the normal criteria for growth are met (the 'No growth due to occupation' function is currently bugged - cities grow normally).
• Second, their Culture and Science output suffer a 75% penalty, while Production and Gold output suffer a 50% penalty.
• Finally, in Rise and Fall the city suffers a -5 Loyalty penalty per turn, which can be negated by permanently stationing a garrisoning unit inside.

A city will remain Occupied until its previous owner agrees to "Cede" the city through diplomatic negotiations (usually as part of a peace settlement), at which point the city will become fully functional again. Note that the previous owner will hold a grudge forever, though - this will sour your diplomatic relationship with them and their allies, until or unless you decide to return the city.

The city can also become fully functional again if the previous owner is eliminated from the game.

This excerpt comes from Gamepedia's article on City Combat.

The website also provides an overview of all the game's icons.