Help me find a movie i've seen in my youth

I have not much to go from but I hope my vague description rings a bell for anyone.
I remember the main concept of the movie having a big impact on my then young mind and I would like to rewatch it.

I’l start naming what I can remember about the moment in no particular order:

I must’ve been around 10 years old(give or take), in a vacation park with my family so we only had Film 1 channels on the bungalow tv. (I’m 27 now)
I’m 70% sure it was on Film 1 Sundance
I’m 90% sure it was a French movie(or at least spoken in french)
Im 90% the setting of the movie was something like paris, or at least an artist figure living in a city

It’s about an artist (either a musician or a writer)

The story follows him as a main character, i believe most of it is about how his life goes, his career, women, the art he pursues. (of this im honostly not so sure.)

What stood out to me and what has always captivated me is that a part of his personality
(kind of like the jungian shadow self/ or maybe even a bit schyzo) is displayed as a seperate humanoid puppet like creature that the main character can only see. He has conversations with it like he’s having moral battles inside his own head.

The character that represents this looks like a caricature of the main actor, with long legs and arms and a big head.

I don’t really remember what time period the movie wat set in but it wasnt very modern of futuristic.

I realise this is pretty vague but this is all i can get to mind.
I hope someone recognises anything of this.

It was Gainsbourg - APPARITION DE LA GUEULE - Extrait 1 - YouTube