Liverpool has a great team, and I agree with you that Liverpool doesn't need to do much in the transfer window since they have a good squad that can compete in the UEFA Champions League competition and the Premier League or any other competitions they will play next season.
It has become a tradition for any club to carry out activities when the transfer market opens, even the greatest teams will enliven the hunt for players to add depth to their squad. Liverpool will look to strengthen their squad after failing in the UCL, especially since several key players such as TAA have left for Real Madrid.
I know that Liverpool will sign players when the transfer window reopens again, but they won't be as active in the transfer window as their rivals like Manchester City and Manchester United will be because Liverpool's squad is okay, and Arne Slot has few positions to strengthen in his squad.