I have the exact same experience as you. I usually take comments like this with a grain of salt, especially if it’s a very general and non-specific complaint.

This is a phenomenon about Apple and some other companies I’ve never fully understood: charitably, there just are people with 1% setups that hit a whole class of bugs in Apple devices that I haven’t seen in 15 years or so

Good for you. Go for open water swimming every day (which Ultra should be perfectly capable of) and see if GPS works reliably. See my reply to parent comment for more bugs.

GPS/distance going terribly wrong when swimmimg, action button sometimes just not doing anything, screen going blank (thinking I'm not wearing it) after workouts randomly, not to mention the original Alpine loop started to break completely in 6-7 months.

I had NONE of these problems with older watches despite doing the exact same things.