LineageOS: Chroot Debian closes when I use a moderate amount of RAM

I'm essentially living out of chroot Debian now, and it pretty much works unlike Mobian. But when I reach some arbitrary limit, often when I try to edit several high resolution layers in GIMP, Termux is terminated (or crashes) with no warning, and no slowdown preceding it. I think LineageOS is closing Termux when it exceeds some arbitrary RAM threshold, but with 6gb I know there's a lot more to go around.