One of the standout features of Microsoft Flight Simulator is that it can use satellite and live weather data to inform the game. You can fly through live weather systems, live air traffic, and even have live photogrammetry streamed to the game in areas that support it, streaming high-quality 3D buildings to your game.
All this data adds up, and if you have a data cap, you will want to keep a close eye on exactly which options you are availing of, and how much data is being used. You can access the data settings by opening the Options menu, picking the General Options, then scrolling down to the Data tab. Here, you will find a range of options that allow you to either turn off data streaming completely or pick and choose which features you wish to take advantage of.
You can also set a data limitation within the game itself, meaning the game will automatically turn off data options when it hits the cap.
If you are worried about data usage, the first option to turn off in Photogrammatery, as this will have the smallest impact on your game. After that, the live weather options would come next, as you can use the Weather menu when flying to set any weather conditions that you wish to experience.