Depressurisation? Hypoxie?

[FHRBL]

Hello, By twice approaching Cuesco, SPZO my device suddenly decided to descend as it was a depressurization of the cabin. I was at flight level 210 and on RNAV approach. On the G1000 the altitude flashed at 10800 or 10900 while the airport had to be at 10825ft of memory. I was also forced to put on the oxygen mask because I risked hypoxia. How to analyze this situation?

Thank you for your advice.
When I left SPZO yesterday, entering the cold and dark cockpit, I was asked to put on the mask or go down to a "safe" altitude.

Sincerely to all

[Goran_M]

Did you somehow manage a tail strike?  Check the maintenance manager and see if the pressure vessel is broken.  You may need a new airframe.

[hiddenace]

If it’s a very high altitude airport take the pressure controller from auto and set it to max differential. It will hold vessel pressure until you land at that point a weight on wheels squat switch should open the OFV and depressurize the airplane