During the whole time of playing and using the mod pack, it happened several times that after installing a new version, problems with the game behavior started - crashes, freezes, lags. In some cases I reported the problem here and the answer was basically the same. The mod pack is fine, you have a bug in your hardware or drivers.But without any hardware or driver update, the problems stopped after installing a new or previous version of the mod pack. This fills me with almost 100% certainty that there is indeed a problem in some part of the mod pack. Unfortunately I don't have the time to reinstall the modpack multiple times part by part. 121B is not so much preferred for gaming by me, so I'll wait for the next version of the modpack, maybe it will fix itself again. Have a nice day!👍