Thank you very much, people, for your answers.
What do you call a "long page"? I have sites with 67,000-275,000 WORDS PER PAGE that function with g ads without a problem. Just asking.
The pages do not include that amount of words, but include several photos, so users must scroll down the pages for a long.
What do you mean for "without a problem"? Do your pages show more than 3-5 AdSense units per page?
The problem with long pages is that often users never scroll to the end of the page so you end up with many ad impressions that are never viewed.
Yep, it may be the reason. But pages include a form to leave comments at the bottom, and 0.1% of visits leave one comment and led me to think that a considerable share of visits reach the bottom of the pages. But, as proposed by @martinibuster, I'll use Microsoft Clarity to get sharp data. Are there similar services to Clarity?
What is your AVV?
It's virtually 100% for desktop and 50% for mobile. When desktop visits, I show AdSense units as soon as the page is loaded. But when mobile visits, I show AdSense units when user starts to scroll down. Yes, it's the reason of such low AVV, but it balanced AVV vs Pagespeed, and I get 100% Pagespeed with that solution. I've read the approach by @NickMNS at [
webmasterworld.com...] and I'll try the option of loading the first BTF ad as soon as the page is loaded. I tried the option of loading the ads when users reached a specific position, but the AVV figures were very similar.
Do you have different ad-units for each ad on the page or are they all the same. In other words can you track ad metrics by ad position?
Yes, I have different ad-units. And the units showed on mobiles just below the fold, next to the first pic, offers the best RPM performance, even though they have lower AVV. Yes, it confirms your suggestion :-), and "Low demand is low demand", so I'll keep on analyzing the metrics.
One of my problems is that, when I insert the unit and the ad is not displayed, I leave the space blank to avoid 'Cumulative Layout Shift', so the user experience is poor. So perhaps it would be better not to include the units at the end of the pages.