I've noticed the adsense coverage decreased from 99.96% to 94% starting on Tuesday with 96.21% and today at 94%. Also the earnings dropped by at least 10%. Do you have the same pattern in your accounts?
my coverage is alright, but i've been seeing a lot of smaller ads filling up the big spaces — for example 486px banners in the 728px spots (which looks a bit silly). so i guess that means there are less ads around
I can verify this as well - and across several Adsense accounts. Beginning Tues, about a 4%-5% drop in coverage which is continuing today (typically hovering around 99.9% like everyone else). Never had to run a backup ad for our Adsense blocks in over 8 years until today.
I wonder if this is somehow due to the new Google drive for widespread SSL use announced last week? Maybe somehow this has affected how the Adwords auction house is going to be run from now on?