Could be.
Try and get all of your comps also with similar flood designations, and then similar homes with similar lot sizes, frontage and views, outside of flood zones and compare them to find if there is an impact.
I had this silliness the other day,
an 8 acre property, the back 3+ acres in a flood zone, the front portion is uplands with a manufactured home, no flood zone.
The neighbor, also not in the flood zone, wanted to by the back 3+ acres from the first property, pending a survey. However, when the neighbor realized the acreage was in a flood zone, they were concerned that they would then have to buy flood insurance, if they owned that land.
Flood waters don't care if you own the land or the neighbor owns the land, flood waters are going to flood a flood plain, that's what we give the water permission to do.
