I asked two specific questions: How can I delete [messages stored in iCloud] without waiting 30 Days? And, how do I keep apps from re-enabling iCloud storage without permission?
I know how to turn an app off from using iCloud. I want to know how to keep an app from turning iCloud access back on. Also, iCloud forces a 30 day wait to remove messages stored. I shouldn't have to wait to remove information from iCloud.
[Privacy]
You missed the point regarding privacy. Privacy is about having control. It is not about protection with claims of end-to-end encryption for one app. Having an extended warranty requires iCloud to be turned on and location services enabled. Allowing Apple to track a phone because of warranty is a privacy concern. I shouldn't have to let Apple know what stores I visit, where my extended family lives, where I take my vacations, and where I work simply because there is a warranty on a phone.
Enabling iCloud because of the warranty then provides apps the ability to re-enable themselves to use iCloud without a phone's owners knowledge or permission as such as iMessages did. iCloud is a privacy risk. Every OS update or app update has the potential of changing the settings where suddenly private information is flying off the cloud without the owner's knowledge - the loss of control. Only a limited number of services are end-to-end encrypted. iOS update to 15.4 re-enabled iCloud for iMessages among other apps without asking me. By the time I found out in just a few minutes after the update, all my messages along with other app data were already in iCloud and now there is a 30 day wait to remove - more loss of control. I have had this issue with other apps even without an OS update. iCloud gets turned back on even after being turned off. Another example is that you can't even turn off iPhone from storing "unspecified" health data in iCloud that Apple won't tell you what it is or how to get rid of it.
Other than warranty, because it is mandated, I have no use for iCloud. It doesn't offer me advantages. I want to minimize its use and impact.