Don't know how critical this is, but I wanted to notify just in case.

Prism Launcher 9.1.
Minecraft - 1.21.4.
NeoForge - 21.4.110-beta.
Mods - ferritecore-7.1.2-neoforge.

https://mclo.gs/AZ3rLyr

Oh, and also, comptability sets Java to 17. Is that okay? And is support for Java 21+ planned? (If there's any benefit to it at all)

As far as I can tell from the log, only the refmap cannot be read, which is normal and harmless on Neo. The compat level also should not matter.