My Ad Limiter add-on is down to 19 users on Firefox. Used to be thousands.
It won't work on Chrome at all now. I'm shutting down SiteTruth, after almost 20 years.[1]
Fwiw, I've been using Firefox for 20+ years, I hate ads with passion and yet I never heard of your add-on until just now.
I don't remember what I've used before uBlock Origin, but since its appearance it's basically solved the ad blocking on Firefox and became the de-facto standard for the browser.
You probably lost all your users to it, rather that they all stopped using FF.
I hate to be the guy to say this, but uBlockOrigin outcompeted you half a decade ago. It's the first extension Install on a fresh install and I have never heard of your extension or site.
It was never intended to be a volume product. It was a demo of a system which fetched background info about companies. I'd hoped to license it to a search company. Then Google turned to the dark side and Yahoo gave up.
[1] https://www.sitetruth.com