That depends on whether you’ve done your due diligence.
Here are the reasons why hub motor fail, and why forks, regardless from steel or alloy, break:
1- Forcing the axle into the drop out and causing pre stress.
2- Inappropriate order or direction of washers or locking washers.
3- Insufficient bolts torque or not providing a proper nut seat on grooved alloy dropouts.
4- A cracked, defective or old fork
5- Loose or defective headset
If your motor is poorly installed or your bike isn’t maintained properly, you’ll bound to have horror stories about hub motor failures. Having said this, converted ebike should be inspected more often than regular bikes. (They’ll go faster and for longer distances too!) The amount of torque in the street legal hub motors is not enough to break the fork dropouts.
Yet, we don’t recommend motor installation on Carbon fiber forks no matter rear or front.