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.
If we are taking about title, I will say Barcelona have a high chance of getting the La Liga title, but the Champions League competition is very tough competition with a strong team and players that have experience. Barcelona will find it very challenging and difficult to win the Champions League; their performance is good. I can’t deny the fact,
but still, champions competition is different from La Liga. Barcelona has a tight schedule, which will Make it more difficult for them. Hansi Flick should just focus more on La Liga, where he always has a high chance of getting the title. Bug Champions League title is going to be a difficult one for them to get.