I got on after not playing for a long time, and saw that nothing was remained from my base, looked like a normal random generated terrain. First I thought this is what the server meant about "claim getting removed if the player is inactive for a while" but soon after looking in chat I realized this was a glitch someone has "purposely" done to destroy people's bases, and I was one of the victims of the glitch. The suspected player's username is: PlayssonPvP. Due to the evidence/chat this was happened about 3 hours ago. Now I'm wondering if a high enough staff member is fast enough to be able to restart the server, and start it from a past save. If so please hurry as I'm pretty sure this isn't just me and the guy online, I checked my friends' bases and this happened to them also. I will be sure to leave some evidence bellow. Please hurry!
I'm not aware of any way to reset chunks as player and you were inactive for 21 days so that speaks for inactivity reset.
My bad then. I thought the inactivity only removes your claim, didn't know it removes your base with it. :/
for clarification, It regenerates all the chunks where you have a claim in. This means, your buildings, items, chests, everything. That's why it is looking like it is new. I wish you all the best!