For two weeks, that’s all I do. I just write it down. I don’t tell the team everything that I think they’re doing wrong. I don’t show up at retro with all the stuff I think they need to change. I just watch, and listen, and I write down everything that seems deeply weird.
For a couple of weeks, you observe and write down anything that makes you think “WTF” in your notebook. You are accumulating a list of things that are unusual from your outsider perspective. Later, you can meet with the team or group and review what you noted. An interesting approach.