OP says it has been developed over the course of 12 years. The team is currently 3 junior devs. There's probably a huge turnover.
It's likely there's a lot of history and political shenanigans that OP isn't aware of yet. This could be a sinking ship. If it's a profitable business why is the team made of juniors?
A small company with legacy code that is a huge mess but that is maintained by the same person for the last 10 years is one thing. The same mess in the hands of 3 juniors who don't even use version control means no one with experience has lasted long enough at this company. That's a red flag.
It's likely there's a lot of history and political shenanigans that OP isn't aware of yet. This could be a sinking ship. If it's a profitable business why is the team made of juniors?
A small company with legacy code that is a huge mess but that is maintained by the same person for the last 10 years is one thing. The same mess in the hands of 3 juniors who don't even use version control means no one with experience has lasted long enough at this company. That's a red flag.