Decreasing amount of communication between team members.

  People silently disagreeing with opinions of other team members, but for whatever reason don't speak their mind and subtly start to communicate only what is needed, not engaging in discussions any more and only doing work-to-rule.

This leads to situations where bad solutions can more easily start becoming part of the project, which again leads to an overhead in debugging/fixing/...

Decreasing communication between team members. People silently disagreeing with opinions of other team members, but for whatever reason don't speak their mind and subtly start to communicate only what is needed, not engaging in discussions any more and only doing work-to-rule.

This leads to situations where bad solutions can more easily start becoming part of the project, which again leads to an overhead in debugging/fixing/...