Google analytics doesn't want to show referrals from sites (document.referrer is empty), what's the problem?

Question

Google Analytics

After buying ads on 5 different sites, I noticed that only 1 of them gave document.referrer.
On the rest, the referrer is empty.
I checked if there is an intermediate domain between the advertisement and the advertiser, it turned out not to be.
The advertiser's site is on the http protocol, and the ad is placed on https in all five cases.
Is it necessary to switch to https in order to start showing the referrer in 4 out of 5 cases?
And why only on one of them is the referrer transmitted without problems?
And I also noticed that on the site where the referrer is transmitted without a problem, there is a meta tag in the header, which is not present in the rest: Advertiser's website: dreamcity.uz Websites with banners: daryo.uz - From here the referrer is transmitted kun.uz
<meta name="Referrer" content="origin">
gazeta.uz
uff.uz
olx.uz

Answer 1

Why don't you use UTM tags for ads?