It's normal, mine is the same.
It's because you are using 4g network of your operator, not because you are using mobile internet over 4g. Every operator has 2g, 3g, 4g network. It depends which one you are connected to.
If your operator does not support voLTE and you make a phone call , during the call it will drop to 3g network. After you close, it will return to LTE/4G
If you are connected to WiFi it will not show you LTE.
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