I just finished the K1 Communion Legend Lost Sector on the moon this week, and when I looted the chest, I got another Felwinter's Helm instead of the new Dawn Chorus. I thought the exotics we didn't have were supposed to be prioritized.
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I got a starfire protocol before I got the new one. So it can definitely happen.
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Newer exotics have a higher chance to drop, but they aren't guaranteed to trop, you must understand the difference.