Jon is, and has always been, a bland and predictable nothing character. Sure, he exists, but what has he actually done in a decade? What has been added by such a major new character?
What sets him apart from his Dad (outside of Superman having to work to become what he is vs nepotism)? What does he like that his Dad doesn't? What does he do different to his Dad? Why should we care about him when we have his Dad? He doesn't even have a Kryptonian name.
He arrived already 8-10, so we skipped the excitement of a pregnancy/birth. He immediately started finding his powers, so we skipped to a base-power level with no complications. He palled around with Damian in some meaningless (apparently fun) basically non-cannon adventures, then jumped to Superman-lite.
None of this is remotely interesting, compelling or surprising. None of this established a new character or the start of their journey.
DC have done what pretty much happens every single time a super-hero kid comes in. The safest route to the blandest kid-version of the lead character. There was never a plan for Jon (initially) and DC didn't want to put in the work to make a compelling character for him (admittedly, everything surrounding bringing him in and Rebirth was a clusterfuck). They eventually locked in on "replacement Superman" and now we're stuck with him.
To say nothing about what it has taken from Lois, who was relegated to wife/mother (thank you, Williamson, and to a degree Bendis).
If DC wants to turn him around, in my opinion, they have no choice but to go backwards. Go back and show us his journey. Show Superman and Lois dealing with the pregnancy. Show the years of Clark and Lois being good parents before the powers kicked in. Show us Jon slowly learning his powers over years with his Dad as teacher (and access to the Fortress), and how that is different to Clark who had to do it solo. What new challenges did/does Jon face?
Show his years on Earth 3 moulding him into an adult and actual hero, learning right and wrong, not just his Dad's ideals aand teaching but through experience - i.e.. have him out on Earth 3, a world where good literally cannot win, fighting to be a hero, a supporting cast, loves, betrayals, little wins and big losses, actually making him a rounded and original character rather than a watered down version of his Dad.
As for now? Shunt him off to the future with the LoSH, add him to a multi-versal Justice League, have him be Superman's emissary and live on Zod's New Krypton (also a waste of a decade, bring on Kneel Before Zod!), send him back to Krypton's past, Colu, Czarnia, back to Earth 3, anywhere!
Just give him adventures as far away from his Dad, Metropolis, and everything else that only detracts from his being something fresh and original.
Jon has been around for a long time and I still have no idea why I should care. I have Superman, why do I need a less interesting spare who doesn't even have a cohesive journey to this point that I can read?
To make a lazy parallel, Gohan's journey may have been messy and disjointed but at least an attempt was made to show growth and establish why we should care about Goku's son (until that changed). DC had no interest in doing that, they just wanted to jump to the "Superman but younger bit", the least interesting part.
If you want an indictment of the character, he's been around for a almost decade and pretty much the only conversation around here is complaining that he was aged up (moaning he has a boyfriend is a distant second). The guy has made so little impact that DC made a show specifically about Superman having kids and didn't use the comics version of Jon (in fact, went as far away as possible).
I genuinely hope the next DC reboot wipes him away so they can try again with an actual plan, as what we currently have is nothing but an encumbrance to the Superman mythos.
He's not even that bad, he's just a completely unnecessary extra. I might sound like I hate him but I nothing him. I largely forget he exists until he is actually on panel, just being another Superman, and then I forget him again.