Chelsea is a really interesting team when it comes to the Champions League. They always seem the underdog in this tournament. But they are always one of the teams to be careful against in the Champions League. Because they have played completely different here for long years. It is like they have been caring about this title more than the Premier League title in the meantime. I don't see other explanation to their success here in the recent years. We can give the 2020/21 season as an example for this. While not many people were thinking of them to win the CL title they just made it.
There is a question occupying my mind like whether this would be another season similar to that. But on the other hand I just don't give it much chance. Because we still haven't seen an example of a strong performance. They struggled against even Dinamo Zagreb so I don't know what they can do against the biggest title contenders.
Most teams tend to take the Champions league competition more seriously than their league and Chelsea seem to be one of such teams the season because that is the best explanation to their successful stats in the Champions league and struggles in the league with same players and same manager. I agree with you that Chelsea should not be underated in the Champions league because if their poor form in the league, who knows whether the Champions league trophies is the major objectives for them this season.