They have some unique weapons in them for finishing the main quest, just a few extra rewards for that.

Originally posted by wapachoo:

Completed the main quest, went to starfarer's refuge, and there were three "celebratory cache" quests with unique caches. Is this just.. a thing?

These celebratory caches are bonus items for the mod reaching a new threshold of subscriber counts. The first cache was for reaching 10k subscribers, the second was for 50k subscribers, and the third one was for reaching 50k subscribers!

These are just simple "thank you" items for all of the support that the mod has gotten, hope you enjoy the weapons! I might make more of these if the mod reaches even higher thresholds :D