Yea, I hear you there. This same watch about 6 months ago stopped responding to Force Touch and I was told by AppleCare I could replace it right in the store. Of course when I get there to do that, it turns out to be incorrect. Turn around time was only 4 or 5 day though.Mine did it also.
I took it to Apple and they offered to take a look but I would not have the watch for like 2 weeks.
I said no thanks because I need my apple watch everyday.
I ended up buying a AW5.
What happens if you remove the watch as a data source in the health app on the iPhone? I would think that would stop the counting of extra flights.
What if you install a barometer app like UpHigh. you can have that track changes in pressure in real time and so you can see that reading on the watch bounce around (my range at my desk would be 2-3 feet up and down normally). It seems like the barometer sensor on the watch is broken? I don't think UpHigh uses the phone, so it is the one app I know of that shows continuous readings from the watch; but to be sure, turn off the phone first and then run it.