It is entirely possible that your Cloudflare previews looked unusual to AdSense. Did you visit the Policy Center as suggested and see any specific information regarding the notice?

They didn't mention why. In the last month, I added a new website to the account and inserted some ads on it. but the website is not getting too much traffic. could that be an issue? I removed the ads from the new website and left only one ad unit per page in the old one. Keeping in mind that I was using only 2 ads units per page.
Let's see what gonna happen.

Was the new site approved for AdSense? It used to be that if you had an AdSense account and added a new site to the account that you could go ahead and put ads on the new site. Now every new site is supposed to be manually approved. That started about a year ago: [webmasterworld.com...]

Did you put an ads.txt file on your sites?

Yes, the new website was approved by AdSense. Both sites have ads.txt. I am really confused.

Hi, Did you manage to resolve this issue at all? I'm also experiencing the same problem and it's already been 12 days. I kinda know what caused mine but just wondering how long does it take for google to uplift ones account. :(

Today I got "The number of ads you can show has been limited" in my AdSense account. In the Analytics i found visits from example.com. Who knows how to block these spammy visits?

[edited by: engine at 11:28 am (utc) on Nov 19, 2019]
[edit reason] please use example.com [/edit]

My Ads are back (4 days ago) and revenue normal again but yet the "ads are limited" notification is still showing. WTF is Google doing.

@Tech4. You can block the domain or IP's from example.com within your cpanel/hosting provider panel or install a wordpress plugin. Under which category did example.com fall under on your analytics. As referral?

TIP: Make sure you have an active WAF and spam blocker installed. This seems to work for me on all my sites.

[edited by: engine at 11:27 am (utc) on Nov 19, 2019]
[edit reason] pleaase use example.com [/edit]

@lancremastered it appears in GA as a referrer to the home page (i mean root - '/' )of my website. Could you please explain in a few words how to install WAF and spam blocker or provide a link to such guide? Thank you

That sounds more like 'referer spam', not actual traffic - you can use our search function and find tons of info about how to deal with that. Here's one now: [webmasterworld.com...] with an answer on how to fix it in GA.

@not2easy thank you. I don't actually know whether or not these visits or 'referrer spam' are the reason why Google stopped serving ads on my website telling me about traffic concerns, but I'm going to try WAF from Sucuri.

If you are seeing issues in GA, it might be more beneficial to make adjustments in GA, just sayin'.

the main issue is that I received "The number of ads you can show has been limited" after a few days since this referral spam appeared.