Abnormally high ram usage on idle (NixOS) - eviltoast

My computer over the last week has (after using the computer for a few hours) shown very high ram usage, around 50 - 60% out of 32GB, even though nothing in htop appears to be the culprit with the highest consumer being Firefox at 1.6% ram, even in a tty, around half of my ram is being used up even though no process shows over 0.1% ram. Rebooting does seem to work, but I’d prefer not to every few hours. Do you think it might be an issue with hardware? I did build my pc so perhaps something’s broken?