Why some people say google will ban our adsense account when we have ads on crypto websites/blogs?
Aside from the old rules about faucets, Adsense will likely disable your account for displaying ads other than theirs to your website.
It's included to their Policies.
Or did you mean, you have advertised your site to other websites or blogs?
If that's the case, there shouldn't be any problem with that.
My site won't have any faucets for sure. It's just a blog site with articles. Is that an issue for adsense on crypto?