iPhone notifications multiple times from the in-built Mail app

I use a Fenix 5s with the latest firmware. I have a problem with my iPhone mail notifications. Every time I unlock my phone, all the notifications from the Maill app existing in the notification center will be pushed again to the Fenix. Only happens with the in-built Mail app, no other notification is repeated.
I saw this problem reported in the past with ForeRunner 235, without any resolution.
https://forums.garmin.com/forum/into-sports/running/forerunner-235-aa/119681-
Does anyone knows if there was any progress in this issue?

Cheers,
Botond