What problems and difficulties do you face during deploying and managing production applications?

I would like to create a simplified deployment process to AWS (and possibly, other clouds, like Hetzner, Digital Ocean, GCP, etc) for developers and small/medium size projects.

For the moment I am researching how different projects are deployed and managed in production and what problems they face. Can you share your experience and problematic places for managing infrastructure and the application running in production?