I'd like to suggest support for Folia (https://github.com/PaperMC/Folia) to VanishNoPacket now that many public plugins are adding support.

This may be of interest: https://github.com/TechnicallyCoded/FoliaLib

This plugin definitely does not have the folia support flag in plugin.yml, either.

While I understand what's happening here, I have a suggestion to minimize confusion for other devs who are not familiar with folia.

Explain to them that you wish to have the plugin support folia. Explain what dev steps they will need to take to resolve it. Do not just share a random stacktrace, because it's not super helpful because this stacktrace would not be achieved running the official release.