Hi @Hyacinth_Ali and welcome to the forum,
I’m afraid that’s just the behavior of Asana webhooks; they are known to be noisy. As a webhook consumer, you’ll have to write your code to account for this behavior.
You are setting a filter which should prevent change events but it seems there’s something about it that’s not being properly registered. The only thing I can see is you’re missing a resource_subtype parameter; try adding
"resource_subtype": "default_task",
to your filter and see if that helps.
That action generates a new task so since you’re asking for webhook events on new tasks, you’re going to receive webhooks in this case, right?