I remember that threads which ignored this rule were mercilessly deleted. Perhaps the OP should correct this previously written, to eliminate all possibilities of interpreting this as a violation of the rules.

However, I think that the reservation of giveaway slots through PM is wrong, and it looks very non-transparent.
For example, you may use the giveaway manager created by bitmover to determine the winner, and you can accept more than 16 participants.

https://bitcoindata.science/giveaway-manager/

I am also sure that you icopress, as an excellent manager, can organize a quality contest that will be transparent and where more users will have a chance to win a prize.