@muffinofdoom I managed to fix this issue, what i did was i went to flags:
opera://flags
type in "dark" in the searchbar
and look for Enable Force dark theme on pages from Settings and Easy Setup
switch that to: default
then in Auto Dark Mode for Web Contents
switch that to: Enable with selective inversion of non-image elements

@muffinofdoom I managed to fix this issue, what i did was i went to flags:
opera://flags
type in "dark" in the searchbar
and look for Enable Force dark theme on pages from Settings and Easy Setup
switch that to: default
then in Auto Dark Mode for Web Contents
switch that to: Enable with selective inversion of non-image elements

@sgunhouse Yes
Its located in appdata as it should be, and has full permission to write there, along as its saving my other settings.
The only setting its not saving is force dark mode.
C:\Users[my username]\AppData\Roaming\Opera Software\Opera GX Stable\ ...
I don't know how opera savedata works, so I'm not sure if anything is missing, but from the looks of it, its all good.

@sgunhouse alright. What should I do after this?

Hello all!
I got OperaGX today and so far its far better than any other browser I have tried, the only issue I could really find with it was the 'force dark mode' option.
Force dark mode doesn't force dark mode on all the elements, it would also invert some images contrast which didn't look too well.

What I did to fix this was I went into flags, and under the first dark mode flag i switched it to not invert images and to invert all elements, which worked just perfectly!
Now I have a separate issue which I don't think I'll be able to fix on my own..
I have force dark mode enabled in flags, and settings, but every time I reset the browser (being by closing it, restarting my pc, etc) it disables the setting!

Its quite annoying to turn it back on every time I go back to opera.
Something to note is that even though it says its off, its still on, but it inverts the images and it doesn't invert all the elements, making it look ugly again.

If anyone has a fix, please help!

Thanks.