Modpack Version: 2.6.0-1.12.2
After hour-ish of playing game lags for 10ish seconds every 30 seconds to a minute, caused by various errors, possibly related to “entity spawning packets”. It happens to me and me alone, despite the fact that three others regularly play and don’t have this issue at all.
I was told that “some mod (probably through coremodding) is messing up entity spawning packets” by a modpack dev on the Modded Minecraft Discord, it’s all the information I have on the specifics. Logging out and restarting my Minecraft (I use MultiMC) is the only way to fix this, logging out and back into the server alone doesn’t fix it, and it will lag again after an hour or so repeating the cycle.
EDIT: Forgot to post my log, how I missed this I’ll never know.