Doing keyalls at a certain amount of players, is this allowed?

[ItsFrails]

Hey, so recently looking through the Minehut rules and talking to people in the Minehut community. On my servers I've always done if we hit a certain amount players online at a time that we will do a keyall. So lets say for example, I say in chat at 100 players we will do a keyall. Is this considered advertisement rewards, I'm not directly telling people to advertise and if they do they will get a set reward every time. They might have to advertise multiple times to not even get the prize. I would never be directly telling anyone to advertise, just to get us to 100 players any way by logging on friends or telling people in the Discord etc.