Found in

• Firefox 105.0b9

Affected versions

• Firefox 91.9.1esr
• Firefox 102.2.0esr
• Firefox 104.0.2
• Firefox 105.0b9

Tested platforms

• Affected platforms:
  Windows 7
  Windows 10
  macOS 11.6

Steps to reproduce

1. Start Firefox with a new profile.
2. Reach cnn.com.
3. Click on the Shield icon and uncheck the Enhanced Tracking Protection toggle.
4. When prompted - accept all the cookies.
5. Observe the Downloads Panel.

Expected result

• ETP should be properly disabled.

Actual result

• Two 0 bytes user-sync files are automatically downloaded after Accepting All the cookies on CNN. For more details, please see the screen recording.

Regression range
Will search for a regression range as soon as possible. For the moment, I can reproduce this behavior in all Fx versions tested so far.

Additional notes

• This issue is not reproducible on the latest Nightly 106.0a1.

It'll be nice to get a regression window to see what might be causing this.
It's probably not a Anti-tracking issue since this is happening when ETP (Enhanced Tracking Protection) is toggled off.
Interesting fact that it's not reproducible on latest Nightly 106.0a1.

I can't reproduce this issue on my Win10 system:

1. Release v80.0.1
2. Release v104.0.2
3. Release v105.0
4. Beta v103.0b1
5. Beta v106.0b3
6. ESR v91.0.1esr
7. ESR v102.2.0esr

I suspect this might have been a website hiccup, but Simona should probably try it again on the systems that it was discovered on.

I can no longer reproduce it - marking this issue as Resolved Worksforme.