Freebie bubbles glitch?
The first time this happened, nearly the entire dutch tree was unlocked for no reason. That was kinda fun since it was a one time thing and I could bounce around new lessons a lot. This time I just unlocked new skills and they are already crown level two! Kinda hard to learn now!
(First was Adverbs bubble, next was Health 2)
This sounds like something you want to send a bug report on: https://support.duolingo.com/hc/en-us/requests/new.