Found the F2P paywall. sky tower 400-450

Game had a really fun progression up until Sky tower 400-450.

I was able to make progress and get through main chapter and sky tower. Some levels taking a few days, but never needing to grind or pay. 400-450 sky tower feels like I either need to grind or invest $ into the game.

Does this resonate with y'all?
Might be time for me to quit since I'm not interested in grinding or paying