If you are using Samsung phone then look at the 5G Logo. The dark logo = 5G connected and when it fades then 5G disconnected. It all happens because Airtel is having NSA 5G while Jio has SA 5G. NSA 5G runs on 4G as core network and 5G as add-on while SA 5G works on 5G core network.
Another thing Samsung users can do is dial * # 0011 # and it will show the connected bands and if 5G radio is connected it will show Band 78 and 100 MHz bandwidth.
My brother use Airtel sim and this thing is always there in every area where it switches back to 4G but signal shows as 5G but 5G radio disconnects and a faded logo confirms it.
Check the screenshot. Only on Samsung you can see this. When it is disconnected data deducts from pack as it is actually using 4G radio.
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