Ad serving is currently limited

[londrum]

So I've been getting this warning on my Adsense dashboard for about ten months...

Ad serving on your account is being temporarily limited while we assess the quality of your site traffic. We'll automatically review and update this limit as we continue to monitor your traffic.

It briefly came off for a few days last November and then went straight back on again.
The warning has only ever been for "quality of site traffic" and not "invalid traffic"

The thing is... the ads have never disappeared. They always fill every ad slot on every page and my earnings have been going up every month as I grow the site. My CTR rate is under 0.5%, Active View Viewable is over 60%, so they're all right. My traffic is 94% organic (pretty much all from google). I don't do social media, don't buy traffic either.
And the amount of money they claw back every month for invalid traffic is only ever about 0.05% to 0.1%, so I think that's all right.
None of my ads are masquerading as navigation, I don't have auto ads turned on, don't do sticky ads.
And it's a travel site (in english), so it's not a niche subject either

I'm at a bit of a loss about how to get rid of the warning. Has anyone else experienced it on their site for this long?

[engine]

I've never seen that for any time. It's been and gone, but never actually stayed.
I also can't imagine them monitoring your site for all that time.

[Dimitri]

The thing is... the ads have never disappeared

Being limited, doesn't mean no more ads, or lower filings. It can also mean that some advertisers are excluded from your ad inventory. So , may be you are earning less than you could. But - may be - . No one knows, may be not even Adsense.

[KleanCat90]

Oh for this your fill rate from adsense is restricted alright. Sometimes its a maximum of 1000 ad requests or even at a maximum of 4500 ad requests. I'm guessing your total adrequests per day is not that many that is why you don't seem to see your coverage dip.
To solve it, you will need to check your site traffic and their behaviour on the website as that is where the problem is coming from.

[londrum]

i'm well over 10,000 impressions a day, and looking back months my coverage is always over 99%.
i enabled cloudfare to see if that helps, and i had a

header("Content-Security-Policy: ....)

on there which probably wasn't a good idea with adsense. so i've switched that off and will see if that makes any difference

[Breathofair33]

Hi - where was this configured exactly: header("Content-Security-Policy: ....)

Trying to understand if my AdSense pages has this on pages.

Is your traffic 100% organic or paid, like Facebook?

[londrum]

the warning has disappeared again, so i think i've cracked it
i reckon it was the

 header("Content-Security-Policy: ....) 

that i had on there.
once i took that off the warning disappeared after about a week.
i was allowing all the google URLs on it, so i thought it was okay, but it seems you need to allow all their 3rd party advertisers as well, and you can never add all of those because they are changing all the time.

it wasnt anything to do with cloudfare because i dropped that after a few days.

[Dimitri]

The HTTP Content-Security-Policy response header allows web site administrators to control resources the user agent is allowed to load for a given page.

[developer.mozilla.org...]

So, a mis configured CSP, can indeed block third party scripts and images, this is the purpose.