I've unexpectedly started having this issue too, even with the automatic ram cleaner, menu AND the bepinex mod. Been playing SPT for a couple years now, and this is the first time I've ever had issues, something with the update to 3.7.3 and up. Been watching task manager and it never approaches more than 16gb now with the automatic ram cleaner. I'm about to run a memtest to see if my ram is just failing at this point.
Ram test came back clean. I did some digging and noticed that the ram cleaner in game doesn't clear out standby usage, only active. Even though I'm only showing an active usage of 16gb, in reality almost 25gb is committed and that number grows steadily due to the leak. You can delay the inevitable out of memory crash by massively increasing your page file, the standby will be shifted over from the physical ram, though it still slowly fills up from the leak, even 50gb wasn't enough for long raids. A combination of a large page file plus ISLC was required to bandaid it. I have a feeling it has a lot to do with the AI mods as the standby and committed are relatively stable when in a "quiet" raid preset from swag.