Hi Kent, this has been reported a few times. The cause seems to be coming from the Malwarebytes Browser Guard addon. It tries to block websites and urls it thinks are threats. It also blocks tracking scripts and ads.

You have it installed. If you disable it, the captchas should stop failing. The reason this is happening is because Malwarebytes is giving a old version of this addon to Firefox users that has outdated blocking rules. I'm trying to see if Malwarebytes can either update this addon or if Mozilla can just remove the addon altogether because it makes no sense to break websites mysteriously, confusing everyone and make people wonder what the heck is going on.

Look here how to disable a addon: Disable or remove Add-ons

Btw was the site you were making a purchase on one of the more famous ones? It could help me get a faster reaction from those involved if it was known this was breaking payments on Amazon, Walmart, Apple, Samsung, etc. Thanks.

I don't have that extension (the Malaware bytes guard, and yet i am totally shut out of computer access to a number of websites due to captcha fail. This is exhausting. What else can it be? Thanks.

Etsy is my most difficult and irritating as I have a store there.