Usually a debug session is initiated with configuration from .vscode/launch.json.
That configuration can contain a specific preLaunchTask that kicks off background tasks.
But when you stop your debug session these background task are still being executed.
The given extension offers a new macro-like command that does two things:
Stop active debug session
Terminate all running tasks
Bind the command to a keyboard shortcut (if you wish) or invoke it via command palette (like in the video below)