The 5G standard has 2 main modes - "New Radio" (Standalone 5G) and "New Radio Non-Standalone" (LTE & 5G mix). The "Non-Standalone" mode doesn't benefit from authentication and authorization improvements of "New Radio" (Standalone 5G).
Phones can be connected to "New Radio" (Standalone 5G) for telephony services and to "Non-Standalone" (LTE & 5G mix) for mobile data. It can also be the other way around where phones are connected to "New Radio" (Standalone 5G) for mobile data and to "Non-Standalone" (LTE & 5G mix) for telephony services.
It may be too much to include indicators for every situation. Mobile data is more secure than telephony services and that makes indicators for "New Radio" (Standalone 5G) and "New Radio Non-Standalone" (LTE & 5G mix) telephony services more important.
"Privacy Cell" app on F-Droid already does what I mention above, but I think the OS itself should provide indicators.