You're out date... Malwarebytes is definitely an antivirus product.
Read this...
https://www.pcmag.com/reviews/malwarebytes-premiumThe PC Security Channel on YouTube also did an excellent malware test in which Malwarebytes did very well.
The point is Avast is becoming an over weight, bug ridden, and deceitful product, with its upselling techniques & pop-ups that ignore their own settings.
I'm an experienced IT specialist and I used to recommend Avast to all my customers however many of them have been duped by their expensive offers and upselling, ultimately buying products they don't need. All but the most experienced customers complain its too complicated, too noisy, and offers expensive renewals.
I've used Malwarebytes Free and HitmanPro licensed as second opinion scanners and both found minor malware Avast had missed.
I originally used the Avast password vault - it was rubbish and less experienced users found it hard to use (most now using Dashlane instead).
I know you're a long term Avast user & supporter...
Contact support, you're joking.
They read this forum, all they have to do is act on the 100s of complaints, and concentrate on quality rather than sales.
Someone at Avast actively deceitfully programmed this pop-up.