Avast is adding a tag to my Gmail

It’s already fixed in the latest beta: https://forum.avast.com/index.php?board=15.0

Wrong.
It’s clearly an advertisement that says specifically:
“This email has been sent from a virus-free computer protected by Avast.” with a linked logo and URL to Avast’s site.
The logo itself is a track-able image served by avast:
https://ipmcdn.avast.com=/images/logo-avast-v1.png

There’s posts from 2014 that suggest they’ve been doing this for the free version all along.
Being a PAYING CUSTOMER, I’m extremely angry that this was ‘accidentally’ enabled on the latest paid update.

Yeah… thanks, but… ahhhhh… no.

I’m not beta testing for Avast. Especially after this debacle.

Well, the beta is stable, but that’s up to you.

I attempted to edit the .INI file
There was and is no reason at all to change the ini file manually. Simply making a change in the settings through the GUI will do the job.
I then uninstalled an reinstalled AVAST with the Mail Shield feature
There was no need to uninstall avast. You could have added the mail shield through control panel.
Not to mention the fact that 'auto-update' was removed for existing subscribers
auto-update has never been removed.