After more than 110 hours of gameplay I had moved on to complete the latest achivment to bring the game to 100%. After completing "V for Vendetta" gog galaxy indicates that I have completed all the objectives (in the news of the game) but in the list of the achivments of the game itself the count remains at 95%.

How can I solve? I currently play on "nvidia geforce now" with the account linked on gog.

up? :/

You did get 100% completion, it's just that right now Galaxy is showing some strange bug for all games where at least 1 achievement is not counted in the percentage. You can see on your profile that you are at 100%:
https://www.gog.com/u/effellepi
I noticed this where I unlocked an achievement in a game and it said I had 0% unlocked.

I have the same prob, "reached 100% milestone in Cyberpunk 2077" is displayed on my profile while my GOG galaxy still say 98% achievement completed