No, Windows goes out of its way not to allow a popup window from a background application to take focus. Instead, it blinks the taskbar icon. An incoming call should not start eating the keystrokes you were sending to the active application. Focus stealing isn't totally solved as an issue, but it's certainly regarded as a problem to be solved and not the desired behavior.
That's nowhere close to my experience. Things that steal focus constantly: 1password losing SSO token, UAC for an application's backup, 3CX call coming in, every random thing in vscode, ...
It's not something windows does or can disallow. You just focus the window in the code and that's it.
