Garmin fenix 6x pro barometer issues

Barometer and altimeter measurements were broken by Garmin with a software update about two years ago. Before that, barometer and altimeter readings on my watch were o.k. (i.e. with the expected +/- errors). Since that software update,

• the watch auto-calibrates during the night and shows altimeter readings of +/- 20 m to where I live in the morning without having been moved a single millimeter (I don't wear the watch while sleeping).
• when I go for a run (5 to 10 km on my standard after work run), the watch loses or gains up to 20 m when I return home, i.e. about 15 % of the height above sea level of where I live.
• when I go biking with my buddies, I'm always the one with the most height gained at the end of the day by approx 20 %. The buddies are using a zoo of devices of different Garmin Edge devices, a Fenix 5 and some other bike computers.
• when I go for a run, the watch always shows me about 10 height meters gained at the start of the run, although the road strictly goes down by approx. 8 height meters in that distance.
• when I go to work (from 154 m above sea level to 110 m above sea level), the watch shows me anything from 75 to 150 m above sea level when I arrive. Returning home, the watch shows me anything from approx 100 m to 210 m above sea level.

I consider all of this unacceptable, especially considering the fact that barometer and altimeter used to be o.k. before that software update. On the other hand, I have been told that this is perfectly normal by a garmin support employee in a long phone call (she stated that this is normal behaviour of the barometer hardware in the watch), so I'm afraid that Garmin has decided not to fix these bugs.

I noticed that altimeter works ok if it is set to nightly instead auto. I also can have garmin connect set to allow all time location permission. Only in auto mode it makes correction of altimeter soon after calibration 

Does not work for me, either. Same errors as described above.