I’m going to steal @Philstar’s image here, because it shows what’s going on pretty well. This isn’t a major bug, but it’s been hanging out for a little while and hasn’t been reported in this forum.
Before the 4.2.0 update (or one of the subsequent updates), you were only allowed to forge unique items once per ascension level. I can’t remember whether the game outright prohibited it, or you just saw zero improvement on the item if you tried. I think it was the former, though. Following one of those updates this spring/summer, you became able to attempt to forge unique items multiple times per level. Sometimes it would give no improvement, sometimes a very slight improvement. When trying to forge a refined unique a second time per level, the effect is even more bizarre, as it will lower many of the values. Like so:
Again, this isn’t a game breaking bug, but it’s a bug, so I’m posting it in the bug house.