Help finding the last small flag on "War's Flames Blaze Fiercely"

[Mister Shan]

The last flag I can see. It's surrounded by a broken up wooden fence and I can see a ladder going down to the sewers. I have been walking in circles trying to find where in the Sewers that exit is. I also hit all the levers to lower the water. Anyone else get stuck with this? I have all the other flags as well.

[Witcher]

Watch this YT vid

https://youtu.be/PSwXvad7I-w