https://www.mariehaynes.com/the-august-1-2018-google-update-strongly-affected-ymyl-sites/
Display all of your E-A-T. Your About page should be full of reasons why you are known as the most authoritative business in your vertical. Brag about awards won, press recognition, years of experience and more. Note: We don’t know whether Google actually gets this information from your About page or not. But, our thought is that whatever we can do to help Google understand our E-A-T is good.
Display your author E-A-T. Every article on your site should have an author listed. That listing should link to an author bio that brags about their E-A-T.
Improve the reputation of your business and your authors. You can often do this by getting favorable press coverage. But, know that Google is pretty good at knowing which parts of sites are written by journalists who can be paid off vs staff journalists who are truly uncovering the news. Other ways to improve your reputation include fostering user reviews across the web, increasing the number of testimonials displayed on your site, getting your authors published in authoritative places outside of your site amongst other things. If you are looking for help in establishing E-A-T, my team and I can do an E-A-T review for you and give you some suggestions. You can contact me for details.
Take a good hard look at the products that you are offering. If you sell a product that could be considered sketchy, spammy or harmful to people, then this could be the cause of your ranking drops. I recognize that in some of these niches, competition is fierce to the point of competitors slandering each other with bad reviews. Hopefully Google is able to look past that. If you have real users leaving bad reviews about your products or complaining about your business, then this issue must be addressed.
If applicable, build up product E-A-T. If you sell a diet product, a medical device, or some other health related product, then there needs to be extensive information on the web about this product. You can improve product E-A-T by fostering reviews, generating discussions and having a product that is so good that people truly want to talk about it.