114GB is a full reinstall. Not an update.
MSFS has a program folder (of about 1GB) and another folder that contains most of the game asset files. (this folder contains two folders, OneStore is all the default scenery, aircraft etc, Community is for 3rd party scenery and aircraft). MSFS will check the OneStore and Community folders each time it starts. If there are missing files it will download them.
If you are getting a 114GB update it sounds like your OneStore folder has either gone missing or MSFS can’t find it.
When you get told to update there should be an option to set the location (I think a button on the bottom right of screen titled BROWSE). You need to make sure that is pointed towards your MSFS folder that contains the OneStore and Community folders otherwise MSFS will redownload everything and install it to it’s default location.
You need to check that your install location is correct.