safari app using way too much mobile data

Contact your IT administrator or MDM provider to obtain the latest MDM profile.

1. Is this your corporate iPhone? Then please contact the system administrator of your corporate
2. If it is your personal device, in that case, do you have any profile installed by your corporate/organisation/enterprise/School Management?
   1. Erase the profile added by you If you have installed a profile on your own --> Install or remove configuration profiles on iPhone - Apple ...
   2. Or please contact the system administrator of the organisation who provided the profile to you
3. If you want to turn on SSL trust for that certificate, go to Settings > General > About > Certificate Trust Settings. Under "Enable full trust for root certificates," turn on trust for the certificate. Apple recommends deploying certificates via Apple Configurator or Mobile Device Management (MDM). --> Trust manually installed certificate profiles in iOS and iPadOS ...

A corporate profile installed on your iPhone could potentially be contributing to the inaccessibility of certain features, which may include WiFi Assist, Low Data Mode etc

Here's why:

• Restrictions: Corporate profiles can have restrictions placed on apps and functionalities. These restrictions might be limiting some activity, causing it to be unresponsive or quit.
• Managed Apps: IT departments might deploy specific navigation apps through the profile, potentially blocking certain functions or features.
• Security Settings: Corporate profiles often have stricter security settings that could affect app or function behavior. This might be causing unexpected behavior of an App or functions.

Here's what you can do:

• Check with IT: The best course of action is to contact your IT department. They can explain the restrictions set by the corporate profile and see what is affected. They might be able to adjust settings or suggest alternative apps or features approved for corporate use.
• Look for App Conflicts: See if your IT department uses a different app through the corporate profile. Conflicting apps might cause crashes.

Additional points to consider:

• Even if the profile isn't directly affecting the function, it's still a good idea to check with IT. They might be aware of similar issues and have workarounds.
• While troubleshooting, make sure you prioritize safety. Don't fiddle with your phone. 

By working with IT and considering these possibilities, you can hopefully identify if the corporate profile is the culprit and find a solution that allows you to use the iPhone to your liking.

Go to Settings > Cellular, then turn Cellular Data on or off for any app (such as Maps) or service (such as Wi-Fi Assist) that can use cellular data.

View or change cellular data settings on iPhone

Your mobile data charges are based on usage recorded by your carrier’s servers—not the data usage shown on your device.

Just to clarify, it's important to understand that a single SIM card can actually be used across multiple devices. This means that you can make and receive calls, consume data from any device, including Android devices.

All the call history and data consumption associated with that SIM card is consolidated in one central location: your trusted carrier. It's worth noting that your carrier will bill you based on this consolidated information. Therefore, if you need a comprehensive breakdown of your usage, I would recommend reaching out to your carrier and requesting a detailed itemized bill.

By doing so, you'll have a clear overview of your usage across all the devices you've used with that SIM card, ensuring transparency and accuracy in your billing.