You'd think it's common sense for the outgoing management to inform you of the changes ahead of time. Like, wayyy ahead of time, by perhaps a month or two? "Meh, it's business." 🙄 Btw, in some areas there are laws requiring landlords/property owners to do so.

I wouldn't respond to a handwritten note left on my door demanding lar,get monthly payments to an unverified number! Your property agent has all your correct contact details and rent payments are made automatically to their account. I agree this sounds like a scam and IF it's genuine, give your property company an official complaint for their unprofessional message.