You are right, those warnings in different colors are flag related. If creator of the thread has Type 1 flag active against him, there will "yellow" warning and in case of Type 2 and 3 flags there will be a "red" warning.

In order for Flag Type 1 flag to become active it needs support of at least 1 DT2 member, wholesale forums flags Type 2 and 3 support of DT1 members is needed.