Gun sales are usually determined by social/political trends and threat level that they pose.
2020-2021 saw an all time high in new gun purchases in not just the US, but everywhere else in the world where guns are available for purchase, due to obvious reasons.
The thing which makes firearms stand out from many other things are their resale value. Firearms last and are meant to last. Unless a gun has been horrifically Bubba'd to the point of resembling a wasp's nest rather than a practical firearm, or severely beaten up due to lack of care and maintenance, the resale value of guns do not drop much at all. A lot of lightly used or new in box guns are now innundating private merchant networks like Gunbroker, due to people selling off excess inventory that they had acquired before and see no need to have so much now. New sales may be dropping but people who are still in the market for guns and have the time to browse for deals are probably buying them from private sellers right now.