Unaccouted Swap Memory Usage (leak?)

I'm running GNOME on Debian 12 (Trixie/sid) (ie, the current testing distribution). Packages are up to date, I don't have any super weird configurations (I do run with --mitigations=off), and I've been seeing this problem for a few months. My laptop is a Dell 7424, with an Intel i5-8350U as well as a discrete Radeon 540 GPU. I've noticed what seems to be a memory leak into swap; swap space which is not attributed to any process. For instance, a screenshot below shows a total swap usage of **2,000** megabytes, but htop running as root shows maybe **200** between all processes. No, I don't need to scroll up. This screenshot was taken immediately after I logged out then back in. I suspect (without evidence) that it is tied somehow to the window manager interacting with multiple displays and/or X windows. I could see the unaccounted space being attributed to shared memory being swapped out, but that raises the question of what processes are sharing that memory. Please note that the problem is *not* with memory; it is purely with swap usage. Resident memory is irrelvant; the problem is purely that the sum of the per-process swap usage (displayed in the SWAP column of the screenshot) does not correspond to the total swap usage (displayed in the top of the screenshot, as the label on the SWP meter). The bug is not in htop; I have confirmed that the values displayed correspond to the data in /proc