When loading into any world new or old it gets stuck on 100% and produces a crash log, removing quark fixes the issue
This error was not occurring previously, I believe it has to be a mod conflict as I tested it on a new instance and it worked fine. Just not sure if it's from a newly updated mod or newly added mod.

Here are my logs:
latest_crashing.log
crash-2021-03-14_21.32.19-server.txt

I found the conflicting mod - https://www.curseforge.com/minecraft/mc-mods/charcoal-pit#comments
When I added it to the new instance it actually crashed and closed Minecraft on world load producing this error - crash-2021-03-14_21.58.48-server.txt with your magnets, upon disabling them through configs it reproduces the initial error.

Fixed in update.