I currently use Unity 2018 LTS, because of my 2019 Unity colours are not really good.
For example, the white is not really white but more like grey and the Shadows are really strong too even if I change the Shadow type.
Why is this happening?
This is Unity 2019
and Unity 2018-LTS
If I change the Directional Light Color from light yellow to Full White then it is whiter, but it doesn't solve the Shadow problem.
By looking at the bottom right corner of the 2019 picture, I can see that the lighting in your scene is not auto generated, which makes the colors unsaturated and dark.
Go to window -> rendering -> lighting settings and make sure auto generate is on and now your scene will look normal.
Though I'm not sure why this would be off in the first place
Office Batman's answer works, but I also solved this issue by setting my camera to a solid black color backdrop (since ambient pulled from that I think) and disabling the Flare component that I believe got added to the camera when upgrading from 2018. I have not narrowed it down to exactly what solved the issue, but one of these stopped the "washed out colors" effect I had after my upgrade!