BTW you can adjust the vibrance with the console command "vibrance_vibrance". The default is 0.7.
Thanks for the feedback all, keep it coming!
To anyone interested, I've made some fixes to the vibrance shader that you can download here: https://drive.google.com/file/d/12TNJYSrHAYpEJu5IBqLhZUkup9NLQLuy/view?usp=sharing
It still defaults to a pretty high level of saturation though, so I recommend you lower it to something between 0.2-0.5 using the "vibrance_vibrance" console command (to me, the sweet spot is 0.3).