I have a problem texture painting

I followed a very good tutorial on texturing skin https://www.youtube.com/watch?v=omrYFaDoTeA&t=51s.
And for a bit of context I am on OpenCl so I have a huge problem working on EEVEE since it doesn’t show in the viewport just plain gray. But thanks to blender cloud I could manage to color in real time. By just using vertex color I could in real time add texture in real time and also render in EEVEE which is a huge relief for me.
But now I have kinda of a problem I do not know why but I can not texture well using the texture painting. Is it a problem of setting or did I miss something.

Is it also because I use vertex coloring in some kinda of way. Also the version that the guy used in his vid was probably 2.83 I guess, I use the latest version.
My problem is that I use the brush and instead of painting in some region it just filled the whole character. I am still a beginner in term of shading.