Different streak in the android app and on the web
I have different streak number in the android app (12) and on the web (72). Problem turned up when I used "Streak freeze".
Another strange thing is, that although I used up "Streak freeze", it is not possible to buy it again - it looks like it's still purchased...
12 (now 13) is your German language streak which is not affected by Streak Freezes. 72 (now 73) is your Duolingo streak which is language independent and is affected by Streak Freezes. The Android app displays your language streak.
On November 23rd you had no activity which used your Streak Freeze, but you purchased another Streak Freeze on November 25th, which is why you can't buy it again.
Maybe Duo's team is not aware of this. I have a different day streak on my Android and on my Web account. And this goes long before streak freeze was implemented ( If I recall this correctly, I first started to use the web version and later the Android app). I used streak freeze twice and every time the counter from the app goes down to 0 while the web counter increments correctly. I am currently with 98 days on the web and only 2 on the phone app.