The pending Firefox 108.1.0 update on my Android's Google Play shows this as a newly added permission, I can't find any documentation about why they recently added this.
TAKE NOTICE: It's only shown on an actual Android device, not on the Google Play website!
"Adjust is a mobile marketing vendor. Many of our mobile products use Adjust to determine the origin of the installation by answering the question, "Did this user on this device install the application in response to a specific advertising campaign performed by Mozilla?"
[...]
When you download one of our mobile apps for the first time, if it uses Adjust, it sends an anonymous "attribution" request to the adjust servers. This request describes how the application was downloaded, for example, whether it was downloaded directly via the App Store or through a marketing campaign link. The data includes an advertising ID, IP address, and timestamp."