My objects are stretched when I go to full screen on WebGL

I am working on a Unity project that I have to convert into a website. I use “WebGL Publisher” package in order to build my project into a website. I use the 2020.3.34f1 editor version. I have several issues exporting this project into WebGL. In the Linux platform, it works fine.

But in WebGL, I have that :

I have a first issue about the “compute shader” because WebGL 2.0 doesn’t support compute shader according to Unity - Manual: Compute shaders where WebGL isn’t mentioned and WebGL 2.0 Compute where it’s written that I have to use WebGPU.

So I have to use WebGPU but I wonder why are the objects stretched when I am in fullscreen ? I don’t have any ideas what it happens. Do you know what I have to do to have a fullscreen without objects ( as ship for example) stretched ?

UP ! I haven’t founded the solution yet. Does anyone in this earth has an idea ?