As you know every time there is always a surprising change of course comes from the world of Internet Marketing, especially to its Adsense Publishers, because there is every reason for the absolute rule that the new Publisher in require to follow it. If not, then the impact would be very detrimental.
Then we will discuss around related about the use of Custom Ads.txt where this would refer to the authorization sell advertising to the Advertiser, This is not only for you or other Adsense in some regional but for all kinds of Publishers that exist today.
In Blogger feature you can find this option on Settings > > Search Preferences > > Custom Ads.txt, by default this option will be Disable and you can enable by manual way, if you want your Adsense ads appear on the pages of the website that your own.
But it needs to be remembered, this is not for your Adsense account already associated directly via Blogger page, meaning this discussion only for Adsense Publisher which getting Adsense account outside of the Blogger page.
For example, if you have 3 different Blogs, but only 1 blog just a direct association to the Adsense in Blogger Page, then 2 other blogs must be pair with Custom Ads.txt, if not the ads will never appear on the Blog.
Then how to enable it? that is easy! on the official page of Google already explain that for using Ads.txt feature, can you it HERE, or you can Follow this Guide.
1. Enter the setting of Ads.txt at Settings >> Search Preferences >> Custom Ads.txt.
2. Turn On.
3. Please enter this command:
google.com, pub-ID of PUBLISHER, DIRECT, f08c47fec0942fa0
4. If you do not know the Adsense ID which you have, you can find them in Adsense dashboard menu Settings>>Account>>Account Information.
5. Example would be like this :
6. Save and wait a few minutes, it should be previously blank Adsense ads, has now started popping up again.
One more thing, this way there will addressing problem Adsense ads sometimes appear sometimes not, because you only need to be declare that you are the owner of the original ad inventory slots and exist, if Ads are getting Blank after that, it's normal.
Because many Factor why Ads are getting Blank, one or more Factor is you Traffic are Tiny, Your Keyword is Bad and your Target Country don't have a many Ads Variant.