Versions (Be specific, do not write "latest"):

*Enigmatic Legacy: EnigmaticLegacy-2.10.3
*Curios API: curios-forge-1.16.4-4.0.3.5
*Patchouli: Patchouli-1.16.4-48
*Forge: 1.16.4-forge-35.1.36
*Refined Storage: refinedstorage-1.9.11.jar

Description of a Bug:

When a player drinks from Unholy Grail while on the server this results in a "Saving" Screen and then CTD. Afterwards MC gives the attached crashlog.

How to Reproduce:

1. Be on hosted server
2. Remove the Grail from the Storage computer (Refined Storage)
3. Drink from Grail
4. Behold!

Logs:

crash-2021-01-16_07.40.20-client.txt

Crash Log: Please use a paste site like hastebin.

Looks like it's caused by Blazing Core effects, where it happens when core's ability forces some potion effect to expire prematurely.