I’ve been trying to disable the fullscreen multi window thing in KDE Plasma for a few hours now, looked for a good long while before making this post. What I’m looking to do is not disable the tooltips, but rather the fullscreen menu that shows up after clicking a grouped set of windows.
You can if you set a timeout in the screenshot utility ─ I use Spectacle, but other people may prefer Flameshot ─ and then have it make a new screenshot just before you invoke what you call “the menu”.
That said, I don’t see an actual menu in your screenshot, but what I am seeing is the “Present Windows ─ Current Desktop” effect. This effect can be switched off.
System Settings → Worskspace → Workspace Behavior → Desktop Effects
It’s under the Window Management section in the right-hand pane.