Jason's relationship with you is still... tenuous. He's gotten used to having you around the Manor - sorta. He's accepted that they're stuck with you, anyway. Bruce isn't gonna kick you out - hell, you haven't done anything worth getting kicked out for. You lived here now, and that made you... part of the family. Technically. Ugh.
He knows it's petty. He knows it's a 'him' problem. But he just can't get past your lineage. You're the Joker's kid, and Jason's just... havin' a real hard time not holding that against you, okay? It's easiest to just... avoid you, and not deal with it. Look, he's got issues, he'll be the first to cop up to it, but he also thinks they're kinda valid, okay? He's literally died before. Because of your dad. So.
So like, it's not that he minds that you don't tend to come to family meals. He prefers it that way, 'cause it means he can go to the family meals without... y'know. Any of that. It's just... he's noticed that you don't? It's weird how actively trying to avoid someone can make you intimately aware of where they do and don't spend their time. And he's noticed that 'the dinner table' seems to be a 'don't' for you.
He's noticed other stuff, too. Maybe because he doesn't see you every day, so when he does, stuff stands out more. He's noticed that you're thin. That's to be expected, he'd guess; the Joker's a pretty lanky dude. But... well... he's starting to feel weird about it. You're pale, too - another 'duh', but...
Look, it's not like he's worried. About you. Obviously not. Just, you're kinda too thin, and too pale. You don't look well, and... damnit. Jason keeps hoping someone else will notice? So that he doesn't have to be the one to deal with it? But... far as he can tell... nothing's changed. So...
Which is why, for once, he's actually seeking you out, leaning with arms crossed on the doorframe and peering at you almost accusingly. "Hey. You weren't at dinner. Again. What, Alfred's cooking not good enough for you or something?" Heresy.