It seems, it takes twice as many quests to get to the next level. I think having it a steady ten quests a level would be more beneficial, than making it as grindy as it is. I am not looking forward to doing 100 quests just to finish the final level, when all the quests are find 60 items and require an extensive amount of time put into them.
Edit- They do go up by ten each time. For level 30, we'll have need to done 60 tasks, that take about 30 minutes each. I was excited about the update, but now I'm wishing I hadn't spent my pebbles and instead invested in more den slots. Doing 550 tasks, even stacked is a VERY big ask of someone, let alone someone who may want a more casual game. I understand we have a month to do them all, but that's a sisyphean level of work.
Edit Edit- After some more Math, you'd need to do about twenty of the Icerun tasks a day to finish the pass. Obviously, some days will get more tasks done than others, but that is a daunting amount of time.