T-Deck - wrong location & how to manually send exact position?

[spfmoby]

I have a t-deck plus. I tried to set everything I can to have perfect accuracy in GPS sharing information, but the node seems always far from its real location. Like 1 mile away.
The displayed location in degree/minute/second on the home screen (even if decimal format is asked) is wrong, even with something like 8 or 11 satellites received.
What seems weird is that when I power on the t-deck, the first location on the home screen is quite accurate, then a few seconds later it is updated with the number of satellites in view, and it is now far off. And always in the same wrong location.

I would also like a way to manually send the current location in a text message to a specific recipient, for example if I want my son who has the t-deck to ask for help and send its exact location, even if the rest of the time only a rounded location is shared.