Avast uninstalled but still blocks certain web pages

Windows 10 Pro with most current Microsoft maintenance. Dell Inspiron 17 7746 laptop.
I uninstalled Avast Free and installed AVG paid version.

Even though Avast has been uninstalled it continues to block many valid web pages.
I continue to see https://ipm-provider.ff.avast.com sometimes appear in the web address in Firefox.
I uninstalled AVG paid and now all web pages load properly.

So there appears to be some relationship between Avast and AVG.
I would like to use my paid AVG but I cannot until this problem is resolved.
Suggestions please!

Thanks,
Terry

AVG is part of Avast, they use the same servers, afaik.