What is the game in the screenshot?

It looks to be a mobile game called Dominus, which describes itself as:

A free multiplayer social strategy game.

Grow in power by conquering castles. Gain vassals until you can overthrow your lord and climb the tree to become the Dominus.

Dominus is a slow strategy game. Army movement and resource gathering happen slowly over time. Login, give your armies their orders then check back in a few hours. Chat with other players to form alliances and conquer larger enemies.

The screenshot on their home page (https://dominusgame.net/) seems to confirm this.