This bug was on a Fabric server with about a dozen optimization mods and a few more QOL mods. Originally considered the chance that a mod had somehow added too much information to my player data and I was unable to join the server because of that player data, but repeated deletions of all my player files didn't solve the problem. (I also tried to use a different launcher with my account to join, and still couldn't, so this doesn't seem isolated to the launcher)

After a bit of searching, I found that this was a bug present in 1.18.2, and that not respawning before logging off could cause it. I died and didn't respawn or go to the main menu the last time I was logged on, and am guessing that is the cause of this bug.

I'm using prismlauncher 5.0, all of my mods have worked on the server without incompatibility, the server's mods have had worked fine too, and I tried to recreate this issue in 1.19 modded and 1.19 and 1.19.2 vanilla singleplayer, and still encountered the loading terrain issue. Interestingly, this problem seems to be hit or miss, as my first attempt at dying and failing to rejoin (in vanilla 1.19.2) ended in the loading terrain bug and my second attempt (also vanilla but in 1.19) just brought me back to the respawn or go to title screen.

Hope this gets fixed,

Thank you