Long time, no see.
Came across this while testing something, thought you should look into it.

https://paste.ee/p/0ifPYipG

(I was able to recreate it without any mods so I know it's an issue with either one of Minecraft's libraries, one of Fabric Loader's libraries, or (secret third option) MultiMC. (I know MultiMC has caused problems in the past, I've gotten somethings breaking only under MMC before.)

Something I forgot to mention: I did disable native transport, and that does work.
However, native transport being enabled isn't an issue on vanilla, so I made this issue anyway.

Hello, from what I remember it is a netty related issue, and one of the fixes you were the one to find was to disable native transport as you did again. I don't know if PrismLaunch includes a fix for it, but that's probably something to suggest to those launchers?