There appears to be a bug in the installer which doesn’t realize when the installation drive has run out of space, and it continues to download the same files over and over.
I received three warnings from my ISP last night, letting me know that I hit 75%, then 90%, then 100+% of my allotted data for the month.
I normally download around ~350GB a month, but last night, MSFS installer downloaded over 1TB of data, and was still at ~70% installation complete when I woke up this morning, with the install drive completely drained at 0% available capacity.
There was no error shown by the installer, and it just kept redownloading files.
I had to pay $80 for the additional data plan. This is a costly bug!!!