ᐅ Paint does not provide full coverage

Hello everyone, first of all, even though this might not be the right place for it.
My name is Yves, I am 38 years old and have been building my dream house for 7 months now.
The whole project is taking place in a northern district on the outskirts of the capital city.
I need some advice on the next steps.
After filling and sanding the drywall panels (never doing that again, pushing a 140m² (1507 ft²) ceiling with a roller is really hard work. Hats off to those who do this daily), I applied a 1:1 diluted primer coat with a short nap roller. Everything looked good so far. Now I bought a paint with a coverage rating of 4 and started painting. Despite what I think is a very good paint, it doesn’t cover properly. But only in places where perhaps too much primer was applied (residual drying). I tried diluting these spots with clear water, but that seemed to have no effect. The residual drying still shows through even after two additional coats. What can I do to finally get an opaque finish?
Regards, a confused ratloser

I guess you either applied too little primer or used the wrong type. The paint is probably still being absorbed by the drywall.
Is the wall completely plastered? Then you will likely need more primer, as the plaster also absorbs a lot.

We wallpapered with fleece after priming, and that worked perfectly.