As of some time earlier this month, VRChat has been using a
ridiculous
amount of memory. On opening the client, its memory usage grows continuously until either the application is closed, or your whole system crashes. Hiding all avatars does not prevent it from happening, and switching safety to hide all after noticing the high memory usage doesn't cause memory usage to decrease anymore. Changing worlds doesn't decrease memory usage anymore. This happens in any world, while wearing any avatar, in Desktop and PCVR mode. The same problem is also happening on Linux through Proton.
Attached are screenshots of VRChat's memory usage charts in Process Explorer and Task Manager, the total system commit graph shortly after a crash, VRChat eating up more memory than Unity on Windows, and VRChat eating up more memory than Unity on Xubuntu.