Open Infamy menu in lobby.

Also you can activate Infamy without break(or leave) the lobby.

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When you activete infamy, you can see your actual infamy but your teammate's screen say old infamy.
after go brefing room all player can see your actual infamy.
It's just visiable have not any problem.

example: go infamy "V" → "VI"
"VI" on your screen
still "V" on your teammate's screen
after brefing room "VI" on all player's screen