Check the interface/portal of the hotspot and look though the connection and network sections.
I also use a 4G hotspot so try to cut down the data use as much as possible.
If you are using Windows 10 make sure you change the settings for the connection in use, so it is set as a metered connection.
There are other options to make sure it does not automatically try to update drivers and windows store apps.
In-line compression will also save data and there are a few options.
You can do this with Opera browser for desktop and mobile, and enable the turbo mode.
It has several settings and levels of compression.
You can add a similar 3rd party compression proxy to the desktop browser you currently use.
SkyZip proxy is less reliable and some times is down for days, but when working will make a big impact on data use.
This also has several levels of compression.
Note, added compression can cause an initial lag before the data arrives, but once downloading will finish a lot faster.
You may even notice that you now have a faster browsing experience generally.
This is very useful on shared connections with multiple users.
Mobile browsers make use of AMP optimised pages and higher compression.
You can add this ability to chromium based browsers with the AMP browser extension.
This will swap any sites over to the mobile format if available.
Vivaldi browser allows you to add “web panels” to the side of the browser, which can be used in many ways.
Web panels can be toggled between desktop and mobile (they default to mobile).
Examples that I use;
https://m.facebook.com/notifications (optimised for mobile)
https://mbasic.facebook.com (optimised for candybar phones with java browsers)