Yesterday I read the change log of the fenix 5x-plus last beta , they claimed an improved gps functionality : gps v223.
The previous 5x-plus one vas gps v220 same version name used by 5x last beta.
To make the story short: verified with "code compare" that the two V220 files are identical and downloaded V223.
The upgrade went perfectly and after one hour of "track me" walking It "seems" to me that we have a better GPS firmware.