I deleted my original post because I wasn't in game and didn't see the whole [donator] thing, but it looks to be fixed. Anyways, your mayor rank wont be replaced because of the permissions it gives you such as being able to own a town, access to mining world and trade signs and everything else. To take away mayor means you'd lose access to everything that the mayor rank gives you and you'd be stuck with less abilities than even a builder. RagMan
The ranks/permissions messed up, and everyones ranks like [Mayor] and [President] and [Moderator] were replaced for donators with this [Donator] so for example it was like this [G] [Donator] [$$$$] [Jetscat]. This was just a bug/mess up, it's totally fixed right now. And by taking away mayor, he meant taking it away visually, you can take away Mayor, add [Donator] and still have Mayor permissions, it's very easy too do, I assume it was just a mix up in the Groups.yml, seems to be fine now.
Well it should say donor anyhow, and [G] [Donor][$$][Mayor] Netsui: wouldn't take up that much more space, granted I play on a fairly high resolution so that might be bias a bit.