Actually got relieved seeing a reply to my post, and then it’s someone who spends time on the forums just trolling and not giving actual answers. 
Like me saying “my car makes a noise, can a car expert please help? 
”, and your answer is “well then take the bus maybe…”.
SOLUTION
Okay… So I have spend DAYS trying to solve this myself… But I think I solved it…
I have now discovered that apparently if you use the Wayland driver in Pop!_OS, it doesn’t know how to handle multiple monitors that run at different fps… And the mouse tend to “escape” your main monitor which makes the camera jump.
In my case I have a 144hz and a 60hz monitor. And because 60 doesn’t add well into 144… it can’t figure out the game window and their framerates, which means your game will get locked at 60fps (your lowest fps monitor).
So here is what you need to do:
First, cap your monitor at 120hz, since 60hz is more “evenly” divided into 120hz… If you have two 60fps monitors, just double check they are both at 60fps, and not 60 and 75 or something…
Second, inside Steam you add your Battlenet APP as a non-steam game. Then go to properties and set the Proton version to Proton 11.
Third, add Wow.exe as a non-steam game. Then go to properties and set the Proton version to GE-Proton 11.1 (you need to manually install this proton version using ProtonUp-QT).
Fourth, inside your Wow.exe non-steam game properties, also add this launch parameter: PROTON_WAYLAND_MONITOR=DP-2 PROTON_ENABLE_WAYLAND=1 %command%
Now…
When you want to open Battlenet, you open the Battlenet non-steam game, BUT when you want to play WoW you need to launch the Wow.exe non-steam game. VERY IMPORTANT!
Yes… you WILL need to type in your WoW password every time you open WoW, but this is the solution. 
I already tried Lutris to run Battlenet, but it won’t work for me.
