Won't damage anything, it just may have to use the internal battery for intensive tasks. This would be the case even with a higher watt 99W monitor, given the the fact the 16" MBP comes with a 140W power brick(Of course, with the higher watt monitor, this much less likely to happen). With a Windows PC, it's going to bitch about the power output being too little but it will work fine, just charge slower.
Power output is a detail that is often glossed over when it comes to USB-C Monitors, but it's how they achieved a cheaper price.(I know because when I was 4k USB-C monitor shopping myself, for some monitors the output wasn't the easiest thing to find) I was looking at your monitor, but owning a MBP and a work laptop, I had to eventually bite the bullet and spend the extra money for the U2720Q. There was just no way around it.