I just reached level 13 and a weird bug(?) I’ve had keeps reappearing. For some reason at random level ups I unlock 1 extra piece of Level 7 vocabulary, this has happened 3 times now.
I’ve had this happen with 木星(jupiter), with 火星(mars) and now in level 13 I unlocked 人里(Human habitation) all of a sudden. All for level 7, which I finished a month ago.
Is this a system I don’t understand or is something strange going on?