It does look like Liverpool were hesitant about selling the Firmino when Juventus tabled their initial bid, and it is believed Juventus are now willing to up their offer. The World Cup is coming, he needs regular football and since Liverpool didn’t offer him that last season Juventus will offer him more first team football. Besides he has entered the final year of his contract, and he has won everything at Liverpool, he should equally move for a new challenge like how Mane did.
Roberto Firmino is still an important player for Liverpool, I think for this season Liverpool will try to keep him unless they get a high offer. The arrival of Luiz Diaz and Darwin Nunez is indeed good for Liverpool. But losing two senior players (Mane and Firmino) simultaneously is not a good thing for Liverpool.