Liverpool is doing very well in the league, just like you said and they are also finalists in the EFL cup, down to Champions League, they didn't lost or draw any game until the very last day of the Champions League group stages phase which they dropped points. PSG on the other hand is doing marvellously well in their league as always though and came alive stronger in their last 2 games of the UCL. Right now, between these two teams i really don't know which one will be victorious but I'm sure we are going to have a great and epic game on Wednesday between both of them.
PSG may have come up with a very good stunt in their last two games in the champions league and that gave them the chance to qualify for the next round of the champions league. Liverpool is a very strong team and they are the best for the champions league title as it is now, no any other team by performance so far this seaosn in the champions league has a very good chance like them to win the trophy. Liverpool is a top tier team and their performance this season is very impressive, so I don’t even see them as a team that is going to fall down in the hands of PSG in the champions league. This will be a tough match and no doubt about it, but Liverpool is the best team that is going to win the match.
On a very good day for PSG, only Osman dembélé can change the game for everyone and win them a match. But such a fantastic player does not deliver in every match unlike a player like Mohamed salah which you are very sure will deliver you in every match.
If we are talking about the current form of the teams, we are so much convinced that Liverpool is in better position to win PSG. Even in the Champions League experience, Liverpool is more grounded. So it is fine that everyone expects Liverpool to qualify ahead of PSG but since it is Champions League wonders still happen, especially when there is a chance for a second chance. Like home and away matches.