let us not so focus on the term “memory leak”, let us say “memory issue” 
… else we lost the focus.
In my opinion the memory management of MSFS must be optimized / changed. I mentioned this alread in other thread : an application should not “think” it can allocate unlimited memory. Well optimized applications stop by around 80% of existing physical RAM. The users with 64GIG are already on a the good side, but what should users do with 16GIG RAM - have a 60GIG pagefile ? This can never be an option and these users risc each day that here SSD will fail. In case some features are not possible with the existing amount of RAM, the user can simple not select it or see the amount of details or whatever.
We already find out that memory consume depends a lot from settings like LOD and that MSFS normaly also release former allocated memory if no longer used… also the high ranges around 50gig worked normaly fine.
The only real problem maker for your case which I have currently in mind is accelerated sim rate (slew). MSFS would be not the first simulation which strugle with this feature. May be we need some more test in this direction. ( I normaly not use acceleration speed… all is real time for me ).
But beside of this I allways wonder me about the relation “working-set to commited”. But we can not find out what happend here, that must do the developers with the given infos. ( and in generally why is there not a limitation of used memory ? ).
I asssume at this point the paging started. This is a real huge amount of data and if not a NVME is used also a ‘normal’ SSD slow down the speed extremly ( compared to RAM speed). But also in case you have an application which use only the RAM and this in the >50GIG range, you will notice that it needs time for releasing it, e.g. while exiting the application ( e.g. long DavincyResolve Session)… ( simple speed test is a file copy of a 30GIG file from/to SSD ).
Then is there the cache which windows use for e.g. file-access - so we are by the rolling cache.
Example: open a video on your disc with a size of e.g. 16gig, this 16gig are held in memory from windows. Normaly these kind of memory is statet as “allocable”, but who knows…
In another thread I mentioned RAMMAP. I ask me what happens if I let cleanup the working-set , shared mem, etc… if MSFS in running