As seen, project memory is 46mb, but the types below add up to around 20mb. Its missing audio files
I see sound wave at 3 MB. Are you using all those assets in your project? Your cook and download size are not that far off. As a new feature I don’t want to claim that there are no issues but what may not be apparent here is that your download cook size is significantly different than your file sizes. See you uploaded 104 MB of data but the cook size is 45 MB? We usually expect cooks to get smaller in most cases.
Yeah I am not totally sure if its right or wrong, hopefully this provides an insight and highlights any apparent optimizations that I can do to further improve the project.
One thing I will try to stay away from in the future is making a prop out of every static mesh, instead of simply using the static mesh in the scene. Not sure if that helps reduce filesize (maybe not, but who knows), but that’s one area I want to improve (saves time too).
EDIT: I meant to write 3mb above, type “sound wave” adds to 3mb where its clear that its way more than that, unless it means cook size and not project size
And yes, all these audio assets are being used in the project.
Hello! I am experiencing the same issue today March 23 2024. It has been going on for actually about 6 months. Texture compressing does not work either, nor does the option in UEFN “resize texture import data”.
If you delete the high ticket items and publish, say an asset listed with 100mb showing in the cooked assets in the project size packaged details window are deleted, the project size will still say 399/400mb 99% even after deleting from the content browser and project. I cannot lower my project size and it is inaccurate.
For Example if an asset in the project size details panel shows 7Mb for a Tree_2, I delete all of the Tree_2 assets in the viewport, outliner, and content browser, and foliage,
I push changes to the launcher, and still would show Cooked 399/400MB download size 99% project size.
The game is finished except for fixing these bugs and hopefully other creators can read this post and know they are not alone! 
You have to account cook size, not disk size of assets. Because assets are compressed into what is called the cook build, its less in fliesize after that. Meaning you need to delete more than 7mb to lower it in the project size %