New servers are like that, it will grow in size thereafter until the defeat time stabilizes somewhere between 5 and 10 minutes.

I see, but this is strange and have no reason at all

Well, there is a "reason", they made it dynamically self adjusting because some server is highly populated and the fox used to die in a minute or two whereas low population server have trouble killing it. So whether 5-10 min (given the event is 40 min) should have been the stabilizing time aside(I personally would liked 20-30, for more coins), the self-adjusting bit is very needed.

That said, the starting point they set for new server is quite silly, I can't imagine how any server could ever stabilize to 1000, even if the players are new and weak(I mean no offense there btw, but I can probably deal more damage to the fox per attack then you guys can as a server, unless you got ptws) unless the server is completely dead.

I would have started off at... say... 500k to 5m maybe? I really can't recall how much damage I was dealing at my first fox....