It sounds to me like a junior devops team set up some very costly infra and made a lot of mistakes while learning "on the fly". That's a good example of how "being cheap is expensive": if the company hired veteran DevOps that know wha they're doing - you'd be with a team of 2-3 DevOps that managed the entire system without any burnouts !

A good ratio is 1 junior for every 3-5 seniors.

The problem is that some companies are cheap and not willing to pay high salaries, so they hire a bigger team of juniors and pay more on infra, bugs and downtime...