1- Too many ad-units per page
2- Responsive != optimal for mobile.

My traffic is mostly from mobile

Then your site should be designed for mobile users and the responsiveness should adapt the mobile layout to desktop (Mobile First).

I would recommend keeping only the two ad units above and below your content. You can also add Vignette ads (Auto-Ads) for mobile. Or remove all your ads and use Auto-Ads outright, it's a feature that lets AdSense select the optimal ads placements.

Finally, if you have been only approved for 5 days you will likely need to wait a few weeks before AdSense fully crawls and includes your site in all the right auctions. Also RPM is niche specific, you may simply be in a niche or geo-location (or in no specific niche) for which there is very little interest from advertisers and the RPM you are seeing is what you can expect. But I would give it time.

So I don't know what's the problem.

They told you that "some" of your ads. If you look at the active view stats for each of your ad slot
you'll figure out which ones are really seen and those which are nearly never seen . Your bottom ads are certainly see by only a small fraction of visitors.

Too high in the page is not good either because, chances are that people scroll before the ad is loaded. Especially on mobile.

5 Days is no long, as said. It will take months to have a general idea of how your site is performing (or not). Did you use other ad networks before? I mean, to have something to compare with?

Usually, it's admitted that the average RPM should be more or less around $2, but it can highly vary from one site to another, depending of a lot of factors, as well as the niche, volume of traffic, profile of visitors, ...

Yet, I'm facing really really low RPM. (min. 0,02, max 0,07) and of course I'm not okay with it. I'm looking for advice to increase this.

There is a monthly thread devoted to Adsense struggles. Unfortunately there are no concrete answers on what causes drops, low earnings, and how to improve. Here is the latest thread… [webmasterworld.com...]

I also try to tell you the positions of my banners on mobile, to see if it's wrong or could be improved:

You list "rectangle" and "horizontal" banner. Aren't they the same, especially on mobile. How are your ad dimensions varying, specifically? Are you using responsive ads?

If using responsive ads, look at Adsense > Reports > Creative Sizes. You'll see how the different ad sizes are performing.

In my personal experience, ads above the header generated near zero revenue. As mentioned, readers may have already scrolled down before the ad loaded, or that ad placement suffers from ad blindness.

Hello nickmns, thank you for your message. I've removed my adsense and enable the auto-ads, but after the first day the RPM falled down to 0,01. Should I wait for this function too?

Hello Dimitri, thank you for your message. Honestly, I know a guy IRL into the same niche and geo of my website. And I know he is earning well, almost 15-20k/year. His RPM is the average, so I don't think it's a matter of my niche or geo

Hello skaterpunk, thank you for your message. Yes, I meant responsive ads. I check the report but every ads is generating few cents RPM, there isn't much difference...

so should I just wait a month or so?