The app shutting down does not automatically cost nothing. If all users move to the official app the server resources still are used but the users would at least see ads.
Realizing you can’t know everything, don’t know what you don’t know, and respecting other people can have had different experiences than you. All without judging yourself negatively for those realizations. They just are facts. No need to be hard on yourself if you put in sincere effort.
Everyone fails sometimes. Take every failure as a learning experience. Taking it personally and feeling emotions doesn’t actually help the problem - that you made a mistake and need to just learn and move on. Focus on the future, on the problem, on now, not the past. If however you make a mistake and get defensive and don’t learn anything then yeah it’s only a toxic thing on you. Learning from it helps you grow.
Masters of subjects don’t learn overnight. They learn over years, decades, a lifetime. In that time they make countless mistakes. But they persevere and don’t let it affect them emotionally and they grow into those masters.
I make mistakes daily. I’ve thrown away hundreds of thousands of lines of code in my career because it didn’t work as expected. But each time I grew a little and learned something to make the next iteration better.