When you have a team that size you're looking for a couple of senior developers to act as mentors for the others. Often with the right people these relationships naturally develop but sometimes not.
We were all senior. We all got along well. We split into smaller two or three people project teams and worked siloed from everyone else.
Nobody knew what anyone was doing. The lead was stretched too thin. One project would flounder while he focused on managing the others. It was just a mess.
It didn't help there was some low performers on the team constantly slacking off but that was part of the problem room lead wasn't seeing these problems.