Stamina is so low

Stamina is low, and the event difficulty is high. It feels like they want you to spend money, otherwise, you basically can't clear quests. Then, after waiting for the plane for a long time and using up a lot of stamina, it finally appears. The stamina from ads is also decreasing, and sometimes there's none at all. Before, you could get a stamina box by watching ads, but now you can only buy it with diamonds. I've never seen any of those prize draws for stamina mentioned on the official website through comments.