You have to wonder how many pilots who pass the assessment, to go into a hold pool, ultimately get let go, really want to go through the process again? Obviously Jet2 can be very selective, I wonder if this attitude will leave them short of candidates in the future, considering the other options for pilots at the moment.
You do realise that all hold pools in airlines expire though, right? BA used to be two years, Jet2 was one year until COVID. Not sure about the other majors who have hold pools. If candidates in those hold pools refuse to reapply to those airlines, fair enough. I wouldn't do that, I'd just want to keep trying.
I'll say this again: It's not personal, it's business. As someone alluded to earlier, the reason for no feedback given is more likely a HR legality issue. Imagine the fun am employment lawyer could have picking apart a recruiter's words on an email.
I've been in J2 a while and know the culture here. You are rewarded for constantly working hard to improve. Go away and throw everything you have at learning about the Company, its culture and have a think about some strong examples of when you've demonstrated the required competencies for a potential command here. If you do this and arrive at the interview looking well-motivated and full of potential, you'll get a good score. Don't turn up looking like a 'Career First Officer'. I'm not giving you any more specific tips as we don't spoon-feed people in this airline. 'Meritocracy' is the DFO's buzz word at J2, and they mean it.
Good luck.