what is that ghost icon for? It doesn't go over 18 for me

Its when you lose your streak you get the highest number. Its like the badge of honour. Also it only shows when you are on your highest streak like @levelsio lost at 200

Yep, it's your streak high score, a.k.a. ghost streak 👻️

Probably can be explained better but I can't edit now. Its just your highest streak. If your current is your highest then you won't see it but if its not you will see your highest streak :)

ahh got it! Now it's obvious, but I actually thought it was consecutive days I went missing 🙈