I think this is a question that belongs here thematically: Are Flying creatures like falcons affected by the negative effect of "Shallow Sea"?
"Non-Flying, non-aquatic creatures in this zone are hindered and roll one less die when making a non-spell attack."
It is clear that they don't get hindered, but if a Flying creature makes a melee attack against a non-Flying creature, it must lose the Flying trait until the end of that attack action (Rulebook page 15) - so they also would roll one less die...?