How frequent?
How consistent?
Is it the entire watch face?
For example, it may be this bug/glitch:
Sometimes I can swipe up or down for notification or control center, but sometimes I can't with the Series 6. It feels like a software issue. When the watch display is on the always-on display mode, it has no problem with the swipes. Even after I restarted the watch, it happens again...
forums.macrumors.com
In which, the only solution I know of is to restart the watch. I haven’t experienced the frozen watch face for awhile. Although, because of the previously mentioned issue, I do now restart/reboot my watch at least once per week, including, if I don’t need to charge it, just leaving it powered off overnight — I don’t do sleep tracking.
Another possibility, depending on the answeres to the beginning questions, it could be your hands. There were times when my iPhone nor watch would respond to some taps. I thought it might be the way I am tapping or a sensitivity problem. However, at my employment, we use touchscreen POS systems, which I noticed also often don’t recognize my taps/presses. From simple observations, I’m concluding it has to do with skin drones in some way — I know it’s not about cleanliness.