Google AdWords has quietly made a change to how they handle ECPC, also known as enhanced CPC. Previous, Google would raise your max CPC bid by up to 30% but Google is removing that bid cap completely. Google wrote in their help document "We’re now removing the 30% bid cap to fully account for differences in conversion rates across dimensions like audience and location."
Google explained that "this means you generally won’t have to set bid adjustments when using ECPC." "You may still want to set a bid adjustment for mobile, as ECPC doesn’t adjust for the difference in conversion rates between mobile and other devices," Google added.
Here is a screen shot of the announcement, which is linked to in the alerts section of some AdWords accounts:
@zgromadzenie notified of this change this morning.
@zgromadzenie Hi Krzych, thanks for your inputs. I'll be sure to pass this on as feedback for our product teams. -Adi
— Google AdWords (@adwords) May 10, 2017
Forum discussion at Twitter.