Are you sure these coins (regardless of what the correct number is) are held as "national reserve" and not just as regular seized assets where the federal government seizes from criminals and eventually auctions when the court process is over?
The difference is fundamental...
Except small countries like El Salvador and Bhutan that get bitcoin from mining and investment, other countries have bitcoins from seizures. They seized those bitcoins from criminals, hackers and only store bitcoins temporarily and history shows that they will liquidate, sell those bitcoins on the market when they see it's time to do it or when legal related issues were solved already.
Another exception is North Korea with bitcoins got from their hack activities.
https://bitcointreasuries.net/governments