The common problem with these young managers are their leadership style. At 10-something people, micromanaging will work and should be done as early product development is like making craft, but as team grow, problem arises.
These young managers have hard time to delegate. This is more apparent with technical founders as usually they are very intimate with the code base. As company grows, C-level need to think strategically.
Thinking strategically and being hands-on, even still commit into the codebase everyday is not healthy both for the person and the team. The said person will burnt out because he/she needs to think both strategically and also performing the execution.
Some of these managers complaints that their developers not growing. Or they have little empathy to the users. The problem is by still owning a lot of execution, it implies that you don't really trust your team.
Ownership is about responsibility and with ownership comes autonomy in making right (or wrong) decisions. You do that by delegating and give the team full trust. They will make mistake, but it's good for the long run.
As a young founders, it's also valuable to seek for mentors in the industry. Start with your investor(s) and their references. It's good to have somebody who already walks the path so you can ask for their counsel and advise.
Or, if you have friends who have already been managing a bigger companies, then you can ask them for their time for mentorship. In my experience, these people aren't shy to share their experience and have chat over coffee.