Custom Filters exception tag not working as expected

[gortron]

I noticed an issue with the Experimental Ad-Blocking Filters > Customer filters setting.

Environment:

• iOS
• 17.6.0
• Safari

Repro steps:

1. Add ||youtube.com^$document as a custom filter
2. Add @@||youtube.com/watch as a custom filter
3. See DNR output which includes:

   {
   "id": 2,
   "priority": 101,
   "action": {
   "type": "block"
   },
   "condition": {
   "resourceTvpes": [
     "main frame"
   ],
   "urlFilter": "||youtube.com^"
   }
   }
   {
   "id": 2,
   "priority": 100001,
   "action": {
   "type": "allow"
   }, 
   "condition": {
   "urlFilter": "||youtube.com/watch"
   }
   }

Expected behavior: youtube.com/ home page is blocked, BUT youtube.com/watch?v=... videos are NOT blocked.

Actual behavior: youtube.com/ home page is blocked, AND youtube.com/watch?v=... videos ARE blocked.

Let me know if there are any other details I can provide for this issue.

[chrmod]

hi @gortron - thank you for reporting. Have looked into this issue and it looks like the block filter for youtube main page should be slightly different. Does this one works for you ||youtube.com/^$document?

[gortron]

Thanks @chrmod!

Doing so updates the DNR output to be:

{
  "id": 2,
  "priority": 101,
  "action": {
    "type": "block"
  },
  "condition": {
    "resourceTvpes": [
      "main frame"
    ],
    "urlFilter": "||youtube.com/^"
  }
}
{
  "id": 2,
  "priority": 100001,
  "action": {
    "type": "allow"
  }, 
  "condition": {
    "urlFilter": "||youtube.com/watch"
  }
}

And the Actual behavior: youtube.com/ home page AND youtube.com/watch?v=... videos are NOT blocked.

Generally, it seems like Exclusion tags are not working as expected.

[chrmod]

@GRadziejewski can you test this please? It works fine on my end.

@gortron when testing do you force-refresh the page? Youtube is using service workers for caching, so the page may load from cache and network filter wont be able to stop that.

[GRadziejewski]

@chrmod On my machines it looks like this:

||youtube.com^$document
@@||youtube.com/watch

macOS:

https://github.com/user-attachments/assets/a1fce53e-5d6a-413a-9dcd-d1416e7e8ab8

iOS (I had to wait a bit for it to work, but at the end check the results):

https://github.com/user-attachments/assets/470473bc-a9f4-4558-a3fc-e9fd48afaf49