I don't think there is much wrong with Liverpool's current squad, of course the fans are waiting for a new star player to be added to the squad, maybe it could be because it would be an impressive innovation for the championship. But as you said the current squad is good enough to compete with Manchester City and Arsenal.
They look good currently but pre season games shouldn’t be what you judge a team performance by, we all saw how Chelsea played well in the pre season last season but performed woefully when the league began. Some team don’t perform well in preseason but play well when the season starts. We will see if the squad is good enough compete soon because the premier league is a league you should expect a lot from even with smaller teams they can surprise you. Let’s just hope they maintain their performance and play well when the season starts.
Liverpool is one of the teams that currently hasn't got a single player in the transfer market and we don't know why they are too passive at the moment when other teams continue to strengthen their squad by bringing in several new players, Liverpool has several friendly matches with positive results, But that doesn't mean we can say that they are ready to compete next season with Arsenal and Manchester City, friendly matches are not matches that show the true performance of a team so we can't guarantee that they will perform well next season even though they achieve positive results in friendly matches this time.
Last season, Liverpool performed quite well, although in the end they experienced inconsistency towards the end of the season due to injuries to several main players, so Arne Slot should try to bring in two or three new players to prevent last season bad luck from repeating , the majority of the Liverpool squad retained last season squad, however, I doubt that they will be able to compete next season if they don't bring in new players now to support and improve the quality of the old squad.