Yes, I agree with you, that when Liverpool faced Arsenal later, Liverpool was actually confirmed from the start as the champion and they faced the match casually, because for them the match would be played in front of their supporters, and I saw Arsenal were quite disappointed after failing to advance to the next final in the Champions League, even so, both teams will show their performance when the match arrives.
Liverpool does not have to show anything more even though in this week's match Liverpool will play in front of their own supporters. Because even though Liverpool lost to Arsenal, the first position is still Liverpool and Arsenal will still qualify for the UCL next season, so whatever result will happen in their match I think it will not change anything for Liverpool and also Arsenal even though Arsenal's position itself could be threatened again if they cannot win the match this week.