Stop Any Android App from Using Mobile Data

The vast majority of mobile phone plans out there these days don’t offer unlimited data. That means most of us have to keep tabs on how much we’re using each month.
Some apps thrive off a constant Internet connection — even when they’re seemingly not in use. Fortunately Android provides a way to prevent any app from sucking data in the background, and there are third-party apps out there that can take things to the next level.
The written version of this quick tip can be found at https://www.makeuseof.com/tag/prevent-any-app-using-mobile-data-android/
how to turn off the notification?
How do you stop Android from asking everytime I open an app to turn it on! Android 12! I hate that warning, and from time to time it gives you a popup to quickly turn on. I know it's off, I turned it off! There's a reason for it!!! Please if u know how to turm off those warning messages ⚠️ let us know. Thank you!
What about when it won't let u turn it off or deny a permission what do I do 😭