This is why you never put a laserprinter on a UPS.
Not only you should not plug it in a UPS (the initial surge when a laser printer is on would likely surpass the power limit of your UPS too), a laser printer and an UPS should not be under the same circuit breaker. I know because due to a limitation to where I lived before, I have to put both under the same circuit breaker. Every time I print something, it is a power event (where I can hear that the UPS temporarily switched to battery powered mode.)
It might be assuming an inkjet, which have much lower power draws: an inkjet will draw maybe 50W. A laser printer are generally in the mid-hundreds at least and some models can get into the high hundreds to low kW, you need a pretty heavy UPS to handle that and still power other systems.
However, surge protection may not be as important. I heard an argument that it is basically snake oil (because an actual surge would normally be much more powerful and beyond a typical capacity they have, and some causes fire.)