This is already supported! KDE has a really powerful "window rules" feature that lets you configure all kinds of properties on specific windows/apps, and focus stealing prevention is one of them. Just right click the app's title bar and under "more actions" you'll see "Configure Special Window/Application Settings...". The rule configuration window isn't the easiest to use, but "Add Property" is how you can set properties on windows that match the new rule.

I agree. The white light these turn on when recording is not enough for the average person to realize recording is happening.

I was visiting a museum yesterday and someone was using these to livestream/record their own (bad) tour. Security stopped someone doing this with their phone earlier, but had no idea what this guy was doing.

That row has a "Y" in the last column so it was actually granted after the extra review. Most entries in the csv were rejected, but a few like this one were eventually allowed it looks like.