Rust stains on painter's fleece - concrete ceiling

Hello everyone,

in our house, we wallpapered the concrete ceilings with painter's fleece.

Now rust stains are appearing in some places on the ceiling.
Do you know if you can simply paint over them or will the stains show through again?
What else can be done about it?

Thanks

Presumably, you did not prime sufficiently. According to the manufacturer's requirements, was the actual amount used really enough?

Usage test:
For the test, moisten the wall with a spray bottle or a sponge. If dark discolorations appear in the form of lines, hairline, or network cracks, priming is advisable. Beading or normally running-off liquid, on the other hand, makes priming unnecessary.

In this case, I would possibly prime thoroughly once again and then paint.

Thank you.
Can you also prime on the painter's fleece, or does that make no sense?

Don't let everything be pulled out of you—how about detailed information:

On what surface (wood fiber, drywall, or reinforced concrete?) and which fleece? What does the fleece manufacturer say? What about the paint manufacturer? What kind of paint is it anyway?