Mozilla Firefox - Fixing Antivirus Errors
https://blog.mozilla.org/security/2019/07/01/fixing-antivirus-errors/
Sounds like Mozilla trying to justify some of it's actions that have been causing users problems.
Not entirely correct, when this issue first crept up, it was AVs (not just Avast) that place their Security Certs in unexpected locations (Firefox areas for security certs) and this wasn't handled well by the browser (not entirely incorrectly). But now there are fall backs to make what would have been a failure more gracious/successful, allowing the user to proceed.
There is certainly a case for AVs and Browser Companies talking to one and other to avoid these sort of collisions occurring.
Thank you @DavidR for highlighting this. I appreciate that the Avast users/contributors here (including myself) are largely fans, but the fact is that Avast (and AVG, Kaspersky, et. al.) abused the Firefox Policy System to crowbar their (MITM) certificate into Firefox in a way that they were told
explicitly was the wrong way to do it. They did not correct that.
So now Mozilla has had to spend time working around the Avast-created problem.
So, to me it "Sounds like Mozilla is trying to mitigate a problem not of its own making".