Search for channel posts generated by incoming webhook using REST API?

Troubleshooting
1

Hello, is there a good way to query a channel for all posts that have been created using a webhook?
I can see that a post - created by a webhook - has the following information set:

    "zfs19y7qttgqjjbcjyz6atu3pr": {
      "id": "zfs19y7qttgqjjbcjyz6atu3pr",
      "create_at": 1646053476161,
      "update_at": 1646053476161,
...
      "props": {
        "from_webhook": "true",
        "webhook_display_name": "Some fancy Webhook name"
      },
...

Is there a better way as to do a brute force “get all posts and check result for props set” using GetPostsFor Channel (Mattermost API Reference) ?

The reason I asked is because people have created Incoming Webhooks but not restricted the channels to which the webhook should post; so I now need to find out on which channels the webhook might have been posted.

Thanks in advance,
Rainer