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.

No

Then just change the rule to not include the debug console…