Thanks for your comments, hope someone will be able to find story

According to "La Manche Libre" the ship was supposed (in may 2017) to be transformed into a houseboat in Poland by french buyers now living there. That could explain the "PHENIX" and Szczecin sign which seems to point to a marine engine polish company. The article in french is at https://www.lamanchelibre.fr/actualite-331573-manche-l-ancien-patrouilleur-des-douanes-vendu-et-transforme-en-habitation
So, since the name not being PHENIX, the ship still need to be in the mystery ship category.

Story is completed so... thanks again

Thanks you brunoh & rarcand for your help. I continue also from my side.

Rarcand, very impressive recognition skill!
Actually I took the picture of Vent D'Amont that you mention, but when I saw the ship today in St Nazaire I was wondering what was the origin of the ship, I was wondering and didn't think of a french built ship, I didn't have the feeling... I was starting to look from Netherlands (as it has a Dutch flag now), then I went to shipspotting and the truth came out ;-)

I think it was a french custom cutter, the VENT D'AMONT (DF40).
Check http://www.shipspotting.com/gallery/photo.php?lid=1099299
and there is that article about it being sold.
https://www.lamanchelibre.fr/actualite-331523-l-ex-vedette-des-douanes-vendue

Thanks, i will try to see what is under paint

Il looks like a custom cutter with a new owner. Some distinctive inscriptions are now covered with a new paint darker than the original one.