Also, decals project along X, so you may want to scoot the actor so it overlaps the wall, otherwise you’ll just see gibberish on the floor - although I feel you’re aware of this.
I attempted to replicate your setup. The letters in your image are partially transparent. I made the first line of text ‘beer inside’ transparent, too. The top line’s Alpha = 128. And it seems to work more than OK.
Unsure at this point what is the issue and why it manifests.
the opacity is not correct
Sadly, this is all the info you’re provided. I was wondering whether this could be caused by the way light is set up in your project. Consider applying the decal in a new blank project just to test it out. It might be easier to pinpoint the culprit.