Just happened again. I think I know how.
You end your daily quest, get the reward, return to the main menu, and switch to another app(s) so the game is unloaded from memory.
Then you return back to the game - it starts loading from scratch and then immediately shows the rewards again.
I believe the right remedy, if the game knows (locally) that the what was done but haven't sent it to the server is to die the timestamp of the game ends together with the reward. Then, if I switch to the game the next day, it shows the reward but knows it's for the previous day, and doesn't break the consecutive days of quests.

By the way, is there any way to restore the consecutive days for me? Thanks

Hi. Are you changing the time of your device?