The defeat marked the third consecutive loss for Liverpool, following a 1-0 loss to Crystal Palace and a 4-2 defeat to Galatasaray in the Champions League.
The Reds had started the season strongly with seven consecutive wins, but have since struggled to find consistency, conceding late goals in their previous two matches.
Moises Caicedo scored a long-range goal for Chelsea in the first half, and Estevao Willian sealed the win with a stoppage-time goal, while Cody Gakpo equalized for Liverpool in the second half.
Slot attributed the team's struggles to a combination of factors, including the summer transfer spending and the death of Portugal forward Diogo Jota in a car crash.
He stated that the team is still working to find its ideal level and needs to bring new players into their style of play, given the limited training time in the past few weeks.
Liverpool had 51 minutes without a shot on target against Chelsea, who were missing several injured and suspended defenders.
Slot praised the team's second-half performance, saying they created enough chances to score more goals but failed to play the final pass well enough.
He expressed confidence in the team's ability to connect with new signings Alexander Isak and Mohamed Salah, stating that the more they play together, the more they will gel.
Slot also acknowledged that the team's build-up play was better in the second half, but emphasized the need to improve in this area.
Chelsea manager Enzo Maresca was not present at the post-match press conference due to a red card he received for celebrating the winning goal, but his assistant Willy Caballero praised the team's performance and the importance of the win.