Ads are certainly not ethical at all, especially if you are in a waiting room, office and so as not to want to disturb, you turn off the sound of the game, with which you are spending time, but nevertheless an ad at full volume jumps in the middle , already independent of the annoyances with these banners and pop-ups. This should go to hell. But I do not find at all legitimate that a dev with many hours of work makes a nice and useful app and wants for this a few Euros to have some income from his work and a user hacks this app to save these few euros. Against annoying advertising companies anything goes, but with the work of others you should not get involved.