I just found this.
I belatedly ugpraded to iOS 17 which then made me upgrade to watchOS 10 (from watchOS 8).
I've had a number of problems including the missing space, which reduces legibility greatly.
But it also doesn't update the heart rate often. Quite often I'll check and it says the measurement is from 36 minutes ago, but when I tap on the complication it shows there was actually a different reading a few minutes ago.
Also, when I first upgraded the Blood Oxygen widget was just missing from my watch face—like a black space where it should have been. I went in to add it again from the phone and Blood Oxygen was listed twice. One makes it show up, the other is just black.
There is a lot that is really buggy because under the list of complications for that bottom location for a complication there is: 1) Under stocks a really long number other than the actual name of a stock (looks like computer code) 2) Under world clock you can only add Cupertino or NYC (was it always that way?) 3) Under spotify it lists both spotify and also com.spotify.client.watchkitapp
And as I said under the top left spot it lets you add Blood Oxygen twice, with the same exact name, one of which does nothing.
There is so little to the actual experience of the watch—just that tiny postage stamp square—that these "little" things are actually quite big. I don't really trust the heart rate readings right now. I open the heart rate app and it's telling me different things than the complication. And it's all just not as nice to look at.
And I updated to watchOS 10.2 today as well, and it's still the same. Disheartening to see you all were having these issues so far back and they're not fixed.