Sanding/painting/puttying painter's fleece

We have glued painter's fleece onto our gypsum plaster, unfortunately somewhat amateurishly, so that in some places small dots/bubbles of what is probably adhesive are visible. We did not repair this but painted over it. Now these spots can be seen in the light.

Question: Is it enough to sand with a pole sander/sandpaper or does the painter's fleece have to come off completely, or how can this be done properly without a huge effort?

Furthermore, we want to repaint a bright red wall white. Should we sand it a bit first or paint over it with high-quality white paint?

High-quality white on top. Otherwise the bubbles. So this is luxury

Loops don't help there because you'll just ruin the fleece again. Actually, it means to brush, as already mentioned, and leave it as it is.

If there is not a foreign object under the bubbles (you can feel it), then try to inject some paste into them with a syringe and then press down firmly.

If there is a foreign object, then cut the wallpaper slightly, remove the foreign object, and then glue it again.

Whether one wants to do this certainly also depends on how many spots there are.