[1.16.5] bug report dimension issue

ive noticed that every time i load too many chunks in any given dimension, be it twilight forest, undergarden, the nether, the end (these are the ones ive tested on), the game sort of stops responding, i can move about just fine, but mobs dont move, theres no sound loading, and chunks dont generate any more, and in the one probe's tooltip, it says internal server error. the game doesnt crash either, it just sort of sits there. closing out the world sends you to the saving world screen, and gets stuck on saving world. i have to close it via task manager, and dont get a crash report.  this is singleplayer only as far as i can tell. i think its a forge error, not any particular mod's error, because ive had it on three different packs while testing, enigmatica 6, stacia expert and sky bees, and they all have different mod lists. i was also able to get the error to replicate in a custom pack that just had the one probe and jei in it.