Then when a game is started it starts another Gamescope session which launches the game in a second XWayland session.

No, it doesn’t start another gamescope. It starts a second Xwayland in the same gamescope instance.

This is still WIP, but will definitely get an option before it’s enabled by default. I too much prefer apps just following my configured placement policy.

It’s an issue from a change made a year ago, which you were just unlucky to hit (and indeed mostly hits Arch, because of live updates).

It’s been fixed in 6.4.1, won’t happen again.

The screen brightness adapts automatically to the windows i focus on, which is a good idea.

That’s definitely not something Plasma is doing… Sounds like your monitor is dumb with “adaptive contrast” or just terribly implemented local dimming.

The screencast portal has been around for 7 years. How is it not enough? It is very much GPU-only (if the receiving program supports it, which nearly all do), and encoding the image is up to the app and does not depend on the API.

It was just moved into a separate repository, nothing’s changed about it

No, nothing has been changed. You can opt in to default to copy because a lot of users asked for it. The default behavior is the exact same it’s been ~forever.

Why would it?

This sounds like a bug that was fixed some time ago - the desktop window is stealing focus when it gets created, so every time the display reconnects to the PC.

Because you’re on Debian with Plasma 5.27.5, you don’t have that fix though.

Well, HDR works in Wine Wayland, and X11 can never do it without gamescope.