May 4th 2018, I received the message
Ads are disabled on one or more of your sites - no ads are serving on one or more of your sites because of policy violations. Please investigate the reasons for this in the Policy Center.
Site status: Disabled ad serving due to site-level violations
What you should do
Resolve site violations to restore ad serving on your policy-compliant pages. Note: You can request reviews of the individual pages or sections, however, ad serving will remain disabled across the whole site until the site violations are resolved.
At how to fix, there is an option 2
Stop ad serving requests
Auto ads: Create a new URL group, select or add the page on which you want to stop serving ads, and leave all of the ad formats unselected. Within 7-10 days the page will disappear from the Policy center. Do not request a review.
Ad units: Remove all Google ad code from this page and wait. Within 7-10 days the page will disappear from the Policy center. Do not request a review.
The page was part of the folder "sitemap", where I have different indexes about the site.
So I removed ads from all folders "sitemap" from all my domains,
May 16th, I discovered, that I have overseen the code for page level ads for mobile phones. So I removed also this.
Now it's 13 days after I removed all ads, much more than the stated 7 - 10 days.
Any experience with this?