Agreed, 2 days is nothing to judge anything but I found something while digging why this happened. In performance reports (by Bid type) for the last two days I earned 0% (zero $) from Placement targeted ads.
Normally, my earnings would be like 60% contextual, 35% placement targeted and 5% interest based.
But there are plenty of advertisers who bid using placement targeting on my site. I even used filters in the Allow/block ads section to filter new placement ads to last 1 day and find plenty of new and old advertisers.
So clearly the down in earnings is because something is wrong with placement targeting ads in last two days for my account.