SpO2 readings are quite inaccurate compared to other smartwatches

Comparing venu2 plus SpO2 readings to:

1) ticwatch 3 pro ultra
2) amazfit gtr 3
3) Hauwei watch gt3

Venu 2 plus readings are most of the times in the range 85-92 while the prementioned watches lie between 95-98 (which is the correct reading range of my finger pulsimeter).
Same wrist, same distance from the wrist bone,
I'm experiencing the same issue with both venu sq and fenix 6 pro solar thus with two other sets of sensors.
Maybe the cause relies in the algorithm?
Please Garmin, fix it.