liquid doesn't flow when placed, liquids already spawned in are bugged, and more issues

i actually wanted to post a video and will do so if possible, but, as it is now, it doesn't seem like i can, so i'll describe it. 

the issue is: whenever i place water, it doesn't flow properly; it either stays still or, even if it flows, it doesn't go all the way, and it seems to wave up and down. when the water is inside a cave, or generated by a structure or something similar, it flows but keeps spreading itself for no reason. it also happens with lava. i do have some videos of it recorded and wanted to put in here a youtube video, but i don't know whether i can or cannot do it. this one aside, the rendering of things is also weird: i can place blocks normally and without lag, my game actually doesn't lag at all, but blocks are invisible when placed until i get really close to them and when something like a door is interacted with, although it opens, it takes a sec to update, becoming invisible and then going to the open or closed state. i'm playing on 1.20.1 with 200+ mods, with a lot of them being addons for other mods, such as create, apotheosis, jei addons and such. i'm running minecraft on graalvm's java 17 with minimal arg changes, if any, on forge 47.3.0. 

since it doesn't crash my game, there's no crash report to post, it's only a minor gameplay thing. i wanted to at least post my modlist, but it seems like the website doesn't allow links?? i was gonna post a pastebin url