I haven't had screen tearing on KDE 5, now 6, in the last at least 5 years with Intel and/or NVIDIA graphics.
This is not a problem of X11 itself.
This is not a problem of X11 itself.
Maybe a years or two until Wayland gets to full feature parity (except for features Wayland specifically does not have like network support and drawing window borders etc.)
In those same two year I expect all app I use to be running native on Wayland as well. (IntelliJ being the main app I'm waiting for and they are making progress)
That's a feature, not a security issue.
Any closed source app could easily contain a keylogger: great feature!
If we want people to run closed source on Linux, we need facilities to sandbox these apps like on other OSes. Flatpak is moving in this direction. Wayland's security also helps.