Regarding FENIX 6 IS NOT FOR RUNNING!

It isn't a problem with the Sony GPS chip. Pretty much all modern watches (except Coros Vertix 2) have the same chip. 

Unbelievable ! I don't understand how people can train with such mistake ! Really !!

Thank you for your answer ! Garmin just replied me on Instagram.  Much better and pro answer than Garmin Belux ! "Please be aware that we aware of the serious GPS issue that 2021 has brought upon the Fenix 6 series watches and we're investigating reports.  The issue seems to be impacting not only Garmin but some of our competitors too"  So yes this nis an important issue.  I'm not crazy !

That was a specific issue that happened at the start of 2021. Garmin didn't just post that in reply to you, don't blatantly lie.

The Forerunner 935 is still available if you want better GPS accuracy.

buy.garmin.com/.../010-01746-00

Which poster does not have a clickbait subject heading!

I use my Fenix 6 for running all the time, hundreds of runs recorded on it and never had any significant GPS issues even once. Distance is always consistent (within +/- 0.5% most days, or maybe 1% on the worst days), tracks never off by more than 10 meters or so. I don't know what OP is whining about.

It sort of sounds like he doesn't even have a Fenix 6 and is basing his (unreasonably emotional) opinion entirely on what he (mis)reads online.

"Hundreds of runs" probably means you have an older model like I do. My 6XSapphire is one of the first batch. GPS works pretty nice in my home area. It has some issues within mountains with woods (the Alps). 2021 models seem to have pretty bad GPS performance

Nonsense. I’ve got a Fenix 6 Sapphire that’s a couple of weeks old now and it’s spot on. Why are you posting utter nonsense?