Maneuvering speed is affected by the weight of the airplane.
If the plane is at max gross weight, it has a better, higher, maneuvering speed.
Conversely at a lower weight maneuvering speed is lower, meaning that you need to fly slower to get safely below maneuvering speed.
Yes, this is one of the few aircraft performance speeds that actually improves with a higher weight!
This all has to do with the wing stalling and G-forces. If you are flying at a higher weight, the wing will need to pitch up higher to achieve enough lift force to pull more Gs.
Also remember that G-forces have everything to do with the change in momentum of the plane. It may be tempting to think of maneuvering speed in terms of the force of lift only, but the aircraft structure is certified based on the G-forces, which are a product of lift divided by weight.
Lift / Weight = G Forces
Let’s try an example. According to my POH for a 1978 Cessna 152 the Maneuvering speed is 104 knots at 1670 lbs(full gross weight) and 93 knots at 1350 lbs.
Imagine a Cessna 152 descending and then rapidly pitching up into a climb. Let’s say this is done at 100 knots. In our fully loaded 152 the momentum of the heavy plane will make it take more force to pull up to 4.4 Gs and reach the design limit. But more force can only be achieved by pulling back farther, and this will stall the plane. However, if the same maneuver is performed at 1350 lbs then the design limit will be exceeded. The wing will produce the same amount of lift (same wing at the same speed and angle), but since the weight is lower the aircraft will undergo more g forces.
This can seem counterintuitive but remember that the aircraft is certified based on g-forces and not directly based on the force exerted on the wing. See the video below for more information.