Received email saying less than 25% of iCloud storage remaining, but actually have 44%

I received an email this morning saying

> Thank you for using iCloud to keep the most important information on your iPhone safely stored. You have less than 25% of your free 5 GB of iCloud storage left. For $0.99 a month, you can get iCloud+ with 50 GB of storage.

But when I checked my iCloud storage, I have 2.2 GB left, which is 44%, not even close to 25%. I didn't do any cleanup between the email and checking my storage (which was less than an hour). I don't share my iCloud storage with anyone.

I checked the message headers, and it looks like it's truly from Apple. The links in the email also look legit, not like a phishing scam. I'm a computer professional with quite a bit of experience analyzing email headers.

Why would I get this misleading email? Is it common?