Route tracking drift problem

I used to run with a fenix 6 pro and I was not happy with the quality of the GNSS tracking ability in bad conditions (like near high buildings), so I upgraded it to a forerunner 965, which has dual band GNSS.

I set up the navigation to use all satellites and both bands, and tested it in an open park but the result is way worst than before!

Fenix 6 Pro - one good example.

 

As you can see, I ran in circle multiple times, and you can see that the paths in and out to and from the park overlap as expected. This track is very good to me.

Here is what i got from the forerunner 965 in a sunny day, and same park:

same running in circle, same paths to get in and out.

At the begnning it was all good, but after the first laps, you can see an increasing drift to the north that reaches 30/40 meters. I swear I cannot run on the water!

The software is version 20.26, the latest at this moment.

What am i supposed to do?

Thanks for your help

Stefano