wrote:

If that's
already happening, will the moisture affect the structural stability
of the stand over time? Any mildew issues?

Almost certainly. You don't say what type of birch plywood you used. If it's the
standard U.S. product sold in 4'x8' sheets at Home Depot, Lowes, etc., the glues
are interior glues. It will not be long before this stuff starts to delaminate.
Mildew will also be a problem. If you used an import, such as baltic birch, you
probably won't have a problem with the glues.

A coat or two of any reactive finish (oil-based enamel, oil-based varnish, epoxy
paint, etc.) will seal the wood and prevent the glue from deteriorating. Make
sure you seal the cut edges of the plywood completely. There are anti-mildew
agents that can be added to paints.

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.