iCloud keeps the messages you thought you deleted.

Deleting a long text thread doesn't really clear it from iCloud. I found that out setting up a new iPhone.

Messages sync across your Apple devices through iCloud, which is the whole point. Delete a thread on your phone, it's gone on your iPad too. Fine. That's what you signed up for.

But delete a long conversation, one with more than 100 messages in it, and something odd happens. It disappears off the device you deleted it from, sure. iCloud, though, only actually removes 100 of those messages. The rest just sit there. You watched the thread vanish, you assumed you got the space back, and most of it is still sitting up there.

Every device you own shows the thread as gone, so you'd have no reason to suspect otherwise. The leftovers only show their face when you set up a fresh device and it pulls a clean copy of your iCloud. That's when texts you deleted months ago come strolling back, because as far as iCloud was concerned they never left.

So your storage climbs, quietly. Deletes that should've freed space didn't, and short of wiping to a new device you'd never know. It's a small thing, but a convenient one for the company selling you the next storage tier.