I found the 10 off :)
But then magic happened and I solved it and now I don't know what I should've learned.. Force of trick habit tricked me into missing this trick on the 1st try. I like how it can be solved in sections where each one has a clear intent. No hidden tricks, just plain old (good) "think before you push". Turns out "nothing" was a 2-off :) Got some strong Forgive Me vibes here.
I like how one can lock themselves in thinking they've just unlocked a lock.