Bandwidth difference between monitors

I compared two scenarios in the same game (kingdom come deliverance 2):

a) GeForce Now 4K 60fps, H265 8-bit 4:4:4, laptop connected to a 4K 60Hz TV

b) GeForce Now 4K 120fps, H265 8-bit 4:4:4, laptop connected to a 1080p 120Hz gaming monitor

In case a), the bandwidth is the full 100 Mbps, while in case b) it's only 50-60 Mbps. Why is this? After all, in case b), the stream should be "heavier" than in case a), since 4k 120 fps > 4k 60 fps