It’s just physics.
Float is great for back dragging. However, going forward the bucket is lower than the loader mount on the tractor so if the bucket meets with resistance, the tendency of the tractor is to run over the top of the bucket. In float, the only force preventing that “run over” situation is the weight of the front of the tractor. So if there’s enough resistance from the dirt, snow, etc. on the forward motion of the bucket as you move forward in float, the front of the tractor heads for the sky. That’s true for any loader where the bucket is floating at a position lower than loader attachment point on the tractor, which would be all loaders in pretty much every scenario. Been there, done that and didn’t think about the potential for uncontrolled lifting of the front of the tractor until the first time it happened to me.
I’ve back dragged our 1/4 mile gravel driveway at about 6 mph in reverse and that high speed back drag is fine. BUT, if you float going forward go slow and be careful. If/when the front of the tractor lifts you need to be able to stop before it gets out of control.