I understand what you say, I'm experiencing exactly the same. Same traffic, less earnings, serious websites, original content, you know the rest. Even so daily earnings are at 50% of what they used to be. I've been browsing my sites from diff ips and isps to see if there is some weird ad taking over my sites but nothing, still the clicks are seriusly less of what they used to be.
I find a slight relation of this with the change G did with their algo and results, so I think I might be getting the same traffic numbers but DIFF traffic quality, interests... also, the adsense problems match the absense of ASA.
visiting my Google Adsense account to find an 'optimisation' message telling me 'i'm missing out on extra adsense earnings.'
I also received that message and honestly I pay no attention to it, I have lower earnings on other site but Adsense insisted on another one to increase ad size. In fact it advises me to put a big ad on my most visited page, almost my gold landing page.
I will not do that.
I know what pages receive the most traffic but putting bigger ads there means giving visitors a click out of my site. I began this journey doing what I love to do, not only for the adsense check. I think we should not look for over google optimization or you will eventually loose more than you think.
I'm not fighting against G, I just know things are not quite the same and I will try my best to keep my traffic up for my sites, not exclusively for the ads, any ad.
Do check on maximillianos advise, some advertiser are very hard to avoid and some are using several domains to overcome adsense block lists.
Good luck.