Upgraded system today, and it broke bottles gaming.
When game launches it used to go full screen and capture cursor and change cursor to the in game cursor theme.
But now when i launch game it starts to go fullscreen then very quickly flashes like its trying to go fullscreen and then alt+tab to go back to desktop.. freezes up system until i force close the app with alt + F4.
The game keeps launching and goes through the intro and stuff but the screen is flickering like crazy like its trying to go full screen then back to desktop, fullscreen then back to desktop but like at 20 Hz or something.. real fast.
I know its my fault for upgrading from plasma 6.3 something rather, to todays version on arch..
Maybe someone has any ideas how to fix it? Or maybe what info can i provide to help?
Ok so the problem was/is that for some reason system doesnt know which one is the primary.
let me explain. I got 3 screens connected. Two of them are on, third one is off. One of them is primary. So i enter game and the game tries to throw the game window on the primary but for some reason it thing that the non primary screen is the main one so the window tries to switch/jump on to that monitor but then it remembers that its not the primary and then goes back to the primary and this loops over and over again for ever and at speed of 20fps so the scree flickers like crazy while the gpu tries to make sense whats going on and on top of that render the game on both screens at the same time for some reason so the system locks up almost.
The fix was to turn off all screens except one.
Launch game.
Make game borderless window in settings (it used to be full screen)
Then turn on the second monitor - the game window jump on to that (its not the primary monitor as per the OS (arch btw) on KDE plasma 6.4 display settings.
Then set the prefered display but you have to select the other option/display in game (this game had the setting)
The window will jump to correct screen.
Then turn off the game.
Turn on the game, the window will jump to the incorrect not primary display.
Go in the settings and change the display to primary.
Play game.
That fixed my issue.
Thank you all for helping me, i could not do this without you all. This community was really helpfull. I look forward to post the next question and resolve it myself.
I had similar issues on X11, try using Wayland. 
I am and was on wayland this whole time. X11 or Xlibre dont have fractional scaling.. and only options to go from 100% to 200%.. my sweet spot is 150%.
I was running X11 up until recently and was running 150% scaling on my 27" 4k monitor just fine.
From what i tested few months ago, there was only option to either 100% or 200%.. Maybe its DE thing? Some DE’s have more options in the settings
What DE were you running?
I would also like to note that this is a workaround not a solution and I personally don’t think it should be marked as such, but I leave that up you.
what do you mean workaround? Someone on the dev team messed up some varriable that confused screen 0 with screen 1. You had to do something - mess around with screen position or something to reset that value, and it fixed itself.
This happened when they moved up the plasma version from 6.3 to 6.4. All updates in previous 3 months on 6.3 had no such problem. And few updates on 6.4 since then i havent had this problem either.
While i cant say where to and what to do exactly to reset that screen position, messing the way i did fixed it and reset.
KDE plasma wayland.