uBlock applying blocking rules for websites it is turned off #3083

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is NOT a YouTube, Facebook or Twitch report. These sites MUST be reported by clicking their respective links.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

This issue is in keep with recent user reports on social media stating that even after turning off uBlock for a specific website it is still being detected, very likely as a direct result of this bug that is causing the extension to still apply blocking rules for websites it was turned off.

Currently using uBlock 1.55.0 with default settings and rules on Firefox 121.0.1 and 123.0a1

I have it turned off for youtube.com, for example

I have created a brand new profile with the only extension installed being uBlock

With uBlock turned off for youtube.com the ads are still being blocked

Debugging the page confirms that it is still injecting blocking rules:

Disabling the extension in the browser addon manager and refreshing youtube resolves the problem, no more blocking rules appear in the website.

A specific URL where the issue occurs.

https://www.youtube.com/watch?v=oACoGd4AZwk

Steps to Reproduce

Install uBlock on a fresh profile
Open any url video
Open the debugger and look for the scriplet blocking rules

Expected behavior

When uBlock is turned of for a specific website no blocking rules should be applied

Actual behavior

When uBlock is turned of for a specific website, blocking rules are still being applied

uBO version

1.55.0

Browser name and version

Firefox 121.0.1 and 123.0a1

Operating System and version

Windows 10