I've moved a sink from one side of the room to the other side and now there is not as much pressure in the hot tap
Why is this

Debris in the hot faucet or angle stop, angle stop not fully opened, kinked or obstructed supply line.

Just the hot? I'm with ma on this. Work back checking to see if you have full pressure to the stop, then to the mixing valve. There is some obstruction and its likely debris knocked loose when you did the new install. Cartridges can clog easily but they can be cleaned easily too.