Chelsea's performance this season has not been decisive and it could be said that it is not very consistent. It is true as you said that Chelsea sometimes play well and are surprising when facing big clubs but tend to lose when facing average clubs so it is difficult to predict the results that will occur Chelsea get in every match they face. Liverpool deserve to be favorites in the league cup final because Liverpool's performance is more promising than Chelsea, but Chelsea also won't let them lose at home and Pochettino won't let his club not win any trophies this season.
I think the nature of this match is very different from normal matches, this is a final. Therefore, the spirit of the players will also be very different, and Chelsea is a team that will be more or less comfortable being underestimated compared to Liverpool. However, this can be considered the only title-winning match for them this season, and marks the club's first success under new boss Boehly and coach Pochettino. As for Liverpool, if they win this trophy, it will be considered the end of Jurgen Klopp's reign.
This trophy is meaningful to both teams, Chelsea is looking for the beginning, and Liverpool is the end. This reason alone is enough to make this final more worth waiting for than ever.
Chelsea is said to be actively practicing penalty shootouts in training sessions, perhaps they are aiming to drag Liverpool into penalty shootouts to determine the winner or loser. We can predict that Chelsea will not be able to choose an attacking style with Liverpool in this match. Counter-attacking defense is the optimal option, so practicing for penalty shootouts is understandable.