(noob) where is all my memory?

[M Nags]

Hey I'm useless at this stuff and hoping for some help. After about 5 hours running my computer starts going reallyyy slow irrespective of what I'm doing and everytime I check my memory is essentially full yet task manager shows me about 3 out of 16GB usage. Surely windows 11 isn't eating up 13GB right!? Simple google search had me alter some stuff in regedit which yielded nothing so changed it back. Turned off notifications, running for performance etc. Is 16GB really not enough for windows 11?

Specs:
CPU: AMD Ryzen 9 5900X
CPU cooler: Noctua NH-D15
GPU: Nvidia GTX 1660 Super
Motherboard: Gigabyte B550 Aoruc PRO AC
Memory: G.Skill Ripjaws V 16GB (2x 8GB) DDR4 3200MHz
PSU: Antec TruePower Classic 650W Power Supply

Limited troubleshooting:

 

[hotaru.hino]

Download and run Process Explorer as an administrator (if you see multiple, run "procexp64.exe"), then sort by "Working Set" and see what comes up.

If you don't see "Working Set", right click on the columns, select "Select Columns", go to the "Process Memory" tab, then tick "Working Set Size".