Moisture! The speed of sound in moist air is different than in dry and in the microcosmos of the trumpet, that is a big deal. Intonation and targets change.
Granted, if one has minimal chops, other issues may mask the effect.
A „moist“ instrument is different than just running water through it first (although that does help some).
This is such a fundamental thing for me that I will not risk playing a gig on a dry trumpet (even although it is only dry for the first 10 minutes or so). When testing trumpets, the first 10 minutes do not count.