The full error is - UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 61.0), this version of the Java Runtime only recognizes class file versions up to 60.0
I first got it when trying to update old servers, this is from a fabric server and I get the same thing when running it on my own machine with no third party.
Java is fully updated