99cents per month is for the 50GB tier.
$9.99 is for the 2TB tier.
You or someone with access to your account would have needed to go into the subscription and select the higher tier for that to happen. It won't happen on its own, and Apple has not increased the price of iCloud at all. click here ➜ iCloud+ plans and pricing - Apple Support
Are you certain it's for iCloud? It could be for a different Apple service. Like Apple Fitness+ or News+, or something else entirely. Where do you see this charge exactly? Apple charges on your payment methods would not identify what they are for specifically. They would just show up as apple.com/bill.