I have no idea why Chelsea want to extend Jackson's contract when his performance isn't that good lol.
Chelsea will be in loss I guess, there's no team want Jackson except Chelsea release him cheaper than his market value. It's really rare to see old players in Chelsea, Jackson will turn 31 in the next 9 years, 31 years old striker in Premier League mostly can't compete with the young players anymore.
Now Jackson is 23 years old, and I like the way he plays, of those forwards that are in the team now he is one of the best. No need to worry about what will happen to him in 9 years, now he is young and full of desire to play, especially since any contract can be terminated, and Chelsea is most likely trying to protect themselves in this way so as not to think about extending the contract with this forward in a year or two. If the team changes the coach, then he can give preference to other players, as now Sterling was left out of the game, although he constantly played with Pochettino.
I am sure Chelsea management has considered all this and taken this decision as a young player they saw potential in Nicolas Jackson and I agree with you that the game is not that bad, the market value also predicts the same thing because since he was brought in from Villareal, his market value has increased by 5 million from 30 to 35 million and maybe that's one of the reasons why Chelsea want to secure this player for a long time. Chelsea don't want Mbappe problem to happen again to Jackson.
For this season Nicolas Jackson has played 3 matches, scoring 2 goals and 1 assist this should be a good start and take a place in the starting lineup. Chelsea will play their next match this week and play as the away team against Bournemouth, I don't want to expect too much from this game but I want to see how Jackson plays. If he can score goals then I can say that Chelsea took the right step by extending his contract for the next 9 years.