Popup window for app locked to an activity switches to that activity

I’m using Debian 12 and KDE Plasma 5.25, which the Debian installer includes if you choose it.

I like the activities feature, but…

If I launch an app that’s locked to a different activity than the one I’m currently viewing, the desktop is switched automatically to the app I just launched. This also happens if an app launches a second app that’s also locked to a different activity than the one I’m viewing. This pretty much defeats the purpose of Activities, which I find very useful.

I’ve got this setup with Debian12/KDE Plasma 5.27.5 on two computers. One of them does as I’ve described, the other one doesn’t. Is there a setting to control Activity switching so that it’s only manual and not triggered by a popup window? I’m damned if I can find it but it’s there somewhere. Has to be.