After having the chunks trimmed the night before, the server is updated to 1.20.4, and this time switched to use PurPur. This did not fix the slow chunk loading, and may have made it worse, we don't know. A bit later once AJ logged on, they helpfully fixed datapacks. Jon's fabric instance also got much slower so that they didn't bother fighting mobs, so didn't realize when they lost their sword.