Ads between levels are a common practice and a great way to keep the app free to play.
We understand why you do not like the ad feature but with all its downsides it is a perfect opportunity to let you play the game for free.

If you don't want to see the ads between levels you can turn them off by making any purchase in the shop.
The rewarded offers like 'Extra time', 'Free booster' and others will still be visible to you, so that you can keep getting extra resources!

Thank you for understanding!