This extension is from Capital One and allowed users to create virtual credit card numbers on the fly when checking out at different sites. I had this extension running last year in Firefox and then it started throwing errors. Tried reinstalling, though issues remained. I stopped messing with it and recently got a new computer and went to install it again (thinking that the issue may have been isolated to the previous computer). Unfortunately, it doesn’t even show as available anywhere in the Mozilla store anymore. I checked Capital One’s website. They still show it as supported by Firefox. I called and wasted my time on the phone for any hour with them and they told me it was still supported (they didn’t actually check with anyone involved), though because they couldn’t provide a way for me to get it (link on their site just goes to the Chrome store), they said they would escalate the issue. I have little confidence that I will hear anything so thought I would try and reach out to those on the other side of this equation and see if anyone knows anything. Thanks in advance!
Sometimes extensions are temporary disabled on our site while we resolve review issues with the developers. It’s also possible for developers to disable listings themselves, so it’s better to check with them.
So whats the answer? CapitalOne says it IS supported.
Well, here it is 20 days after the original post and still no Eno® from Capital One® for Firefox. Capital One is slower at fixing problems than Microsoft. 
Yep, this is ridiculous. I’ve been trying to re-install the add-on since the first part of March 2020, but it just isn’t available. I keep checking at least a couple times a week, but nothing nada zilch.
It would be nice if someone would at least explain what the problem is.
I see this add-on is still unavailable for Firefox. If any of you got this working, can you please share? Thanks