Remove Dirty Vignette - 4.11.2

Hey, my team recently converted a project from 4.8 to 4.11.2, and a vignette style overlay has appeared as in this image.
Does anyone know how to get rid of this, or why it’s even there?

Thanks!

if you are using a custom post-process it is not compiling properly anymore and being replaced with that.

^ Correcto!

Also, bear in mind that the engines built-in vignette effect will perform a little better than a material based one - so unless it doesn’t do what you want, just use that instead.