This could also be called “Planetary orbit” or something.
The anomaly effect would be to say that all ships must have a certain minimum speed, due to the risk of being caught in the gravitational pull of the object.
e.g., minimum speed 0.1 would basically force you to use 2 engines on most cruisers. 0.2 would force 3 engines, possibly 4 for a heavy design. I would think that a minimum speed of 0.1 or so would at least prevent people from using those “brick” fleets. There’s already an anomaly to force you to have an engine but you can use 1 cheap engine and have a ship that’s like 0.03 speed, which I’m not really sure is in the intended spirit of that anomaly.