I get the opposite when I have large dry hop additions during active fermentation. In these cases I have had S-04 go down to 1.006 (1.015 predicted), and VOSS Kveik down to 1.010 (1.016 predicted).AS Nosy said, the FG is a prediction. I always end up 1-2 SG above the predicted for some reason for example. I have no idea why but it's consistent and reproducible.
Lower mash temperature will produce a more fermentable wort.
Different yeast strains have different characteristics as well.
What yeast are you using?
It sounds like it will be beerIdiotic as it may sound, I don't know exactly now, haven't recorded the brand, I was aiming for a weizen, but the yeast was stated to have higher attentuation than regular weizen yeasts. So yes, the fermentation should have stopped at around 1.015 but got stuck at 1.025. I didn't have any more of that yeast and when all revival methods failed I pitched an American Ale yeast. So yes, bit of a jumble.