So, today. I saw the ads.txt warning displayed at the top of my Adsense dashboard.
I was surprised because I’ve added the ads.txt to all my blogs that are monetized with Google ads.
Nevertheless, after clicking on the “action” button, I discovered that the affected site is not even my blog. Probably, the blog belongs to those bloggers that have pasted my adsense ads codes on their blogs after copying and pasting content from my blog.
Anyway, I removed the site from the list of authorized sites and the error disappeared after some minutes.
So, if you are seeing the ads.txt warning on your dashboard, this might also be the cause.