sims download on external drive has filled my computers storage

thank you so much for reading. i apologise for the length i wanted to make sure all the details were here. 

my mac is a macbook air m1 with 245GB storage and is on the latest update 14.5. my external drive is a toshiba with 2TB of storage 1.96TB free

i have had my sims game on an external drive for about a month now. i have had no big issues with it so far. 

i stayed up late to play the new lovestruck pack, when i went to download it the EA App told me i needed to download the base game. my drive was plugged in and it would even let me start up the game. i tried looking on here but there was no conclusion to the thread. i decided to uninstall my game and hope that when it reinstalled it would download with the other packs.

as the game was downloading i got a notification that my storage was full. i was confused by this because 1. my storage was not full and 2. i was installing the game on an external hard drive

i moved large files onto the drive and deleted it from the mac clearing over 40 gb of storage. the downloads continued as normal

less than an hour later the packs are almost done installing and i get the exact same pop up 

i check my storage and yes, it is full. there is 136 gb of system data. i have used omnidisksweeper to locate and clear unnecessary data before, there’s always been some left behind that i could not find. i checked and i cannot account for any of this data. but it is filling my computer.

i am very confused and very tired as i have been at this since 3am and it is nearly 7. my determination has officially been worn and i really need some help on this. thank you so much for reading all of this even if you do not have any advice.

attached is the message i got from ea app and my mac’s storage with system data highlighted.