They do what Magical Dice just did today.
Paused the Signature campaign and start counting the posts so they can still pay same rate.
After that they will post the new rates.
And that's somewhat acceptable way. Still not OK to change the rules during the on-going period, but at least they pay correctly for the post already made.
But is the campaign organisers' responsibility to make sure they have sufficient funds
before each period starts.
Otherwise they could just pay you whatever they feel like each week.
ps. Are there any funds in escrow (devthedev)?