I run an alternative news site for almost 3 years now. My SEO is good. I was earning around $500 a month with Google AdSense, until the ens of June when my traffic dropped dramatically, and now (August 22) I am barely earning $50, and traffic seems to keep dropping. I haven’t got any penalties warnings though. Do you think I was shadow banned or this drop might just be seasonal? Heres a screenshot showing the last 4 months graphics...
Check your all traffic sources. Is there any traffic source you think has stopped giving traffic or gradually dropped traffic as compared to previous months. Check all these reports month wise. You'll get to know which channel is dropping traffic. If it's organic then surely it has to do with SEO of your site. Otherwise there could me many reason. You can check this in Acquisition > All Traffic > Channels report.