Hello. The amount of data used depends entirely on the way that it is used. One of the most demanding tasks on data is video streaming. As an example, on an ordinary screen (not hd), it is easy to consume 1gb in just under an hour. The amount used then tends to grow exponentially depending on the quality of the video that you are streaming or downloading. An HD tv can easily consume 2gb of data or more in one 45 minute episode on Netflix, and that is not including any additional services that you may get from a smart tv to access other forms of media. Aside from the usage from a TV, you must also consider your settings on the hotspot, since users tend to forget to set up a password and leave the Wifi open. Smart devices will scan for open networks and often connect automatically, or inform the user of the open network in order to confirm the connection first, so there could also be other devices connecting to your hotspot at the same time.
At the moment we haven't received any reports from our engineers regarding the issues that you mentioned being related to the upgrade to 5g.
You can also go into your settings to verify the amount of data used on hotspot.
Let us know if there is anything else that we can do for you.