legitimate ebook vendors, is there a list?

Hi Guys


I have recently been getting a tonne of ads on my socials for various ebooks and deals, some of them have extremely good deals, to the point where I start to think they may be dodgy.
Is there a list of "good " vendors or at least of bad vendors, i have tried searching this site for some of the names and nothing comes up

the ones I am currently seeing are

Thriller and horror dot com
book Bub?
and a couple of others that i cant remember now that i have actually sat down to query