One common issue with growing teams with an extensive codebase is maintaining the code quality. It requires tremendous effort to maintain the code base, and manual code reviews often create a bottleneck during the development process.
One standard practice is to get the pull request (PR) reviewed by a senior engineer before merging it into the code base. But developers often get overloaded with reviews as they continue to deliver their regular tasks and might overlook some of the minute details that end up in production. I personally had an experience where a simple missing null check created a cascading error during migration, ultimately leading to corrupted data in production. Human beings tend to make such mistakes, and it is a very common issue.