Barcelona's performance under Hansi Flick is indeed extraordinary, the coach did not need much time in his first season, he immediately managed the team very well as he has shown now, and indeed there is no need to doubt that Barcelona is a strong candidate team to win the UCL title, they only need to maintain their level of consistency in this increasingly tight schedule.
As a Madrid fan, I doubt Barcelona can win the UCL title this season. 
I admit that Barcelona performance is better now after replacing the new coach and in the end Hansi Flick proved that he is very suitable to be Barcelona coach even though he was initially doubted. But no matter how strong Barcelona is now, I am sure it will not be easy to get through all these challenges because there is still Liverpool who is much more consistent and has better quality players.
Hansi Flick is experience manager and he has been able to gets Champion league trophy with Bayern Munich on season 2019/2020 so maybe there is a chances for Barcelona to reach at least the final match but for strong candidates i still placed Real Madrid in the first place this because they are the most champion in this competition and for Liverpool i don't dare to expect more because they are in the transition period of changing coaches