Out of Russia: flag of the city of Tiraspol, Transnistria,
While you can guess that the city is somewhere by a river, there is so much more interesting going on in context.
Transnistria is basically another way of writing Trans-dniester, as in the Dniester river, which runs through most of Transnistria. In the flag, the divide is probably between Transnistria (red, communists’ favourite colour) and the (green) rest of Moldova.
Now, truthfully Transnistria is a non-country, but it’s just so different and detached from the rest of Moldova, it’s like it’s living in an alternate timeline where the USSR never collapsed. Even the flag of Transnistria is literally the flag of the Moldovan SSR.