I had already collected 5 stamps from previous days. Today, I completed a level that should have qualified for an additional stamp. However, instead of being counted as the 6th stamp and awarding the prize, it was counted as the first stamp.
It appears that the progress was reset and started from the beginning. As a result, the expected rewards were not delivered and the experience restarted. Additionally, the Daily Stamps section is no longer accessible or visible anywhere in the game