The thing you need to remember about comics ages and timelines is that yeah it's messy there are retcons at stuff and it will never be clear and perfect. But also, DC has an interest portraying age the way they do. They have an interest in aging Barbara down so she can be Dick's pretty girlfriend with whom he raises a cute dog (and maybe a cute little family next perhaps?). They have an interest in trying to keep Tim young and draw him younger than he looks so they can milk his Robin's popularity for as long as possible. They have an interest in drawing Jason to make him look 40 when Bruce slits his throat, to make him look like a grown man fighting a teenager when fighting Mia even though they're the same age (though i mantain that mia is a little bit older), in having him call Tim kid even though they're the same age, in having him offer Tim a drink and Tim pointing out he's not legal when Jason isn't either. They have an interest in Jason looking older in Jim Aparo's art style in ADITF than he looked in precrisis or in 308. They have an interest in Steph magically looking older in War Games, where she gets tortured and brutally murdered, than the fun colourful round and much more youthful art from her Robin run. There are probably many more examples but bottom line it's not fucking innocent. DC knows how to hire artists that know how to draw children it's really not that hard. Characters who look young, characters who remind you that they are young, create more empathy; which is good when you want the public to continue to root for them, and bad when those characters challenge the status quo or that excess of empathy might create pushback after you decide to have them brutally murdered. DC can't have Batman grievously wounding and causing the death of his underage son, but if he looks as old as Batman? DC can't have Jason making a valid point about vigilantism being unsafe for Mia and relating with her with childhood sexual abuse subtext because it makes the heroes (and especially Batman) look bad, but if it looks like this is a grown ass man harassing a teenage girl, then it's clear who is the villain, it's okay, no problem. DC needs Barbara to be younger so the power dynamic between her and Dick fits their idea of a perfect little nuclear family much better and they can shove Barbara back into the role of Batgirl even though she is very much a girl rather than a woman. DC needs Steph to look older when she's tortured so they can be edgy without people being too horrified at them doing something horrifying, DC needs Jason and Steph to look older on the day they die because young looking= innocent which makes it so much harder to victim-blame. DC needs Mia to look younger than Jason so they can make it look like the good old "good victim/bad victim" dichotomy and even though that's not what the story is actually about, regardless of how much it disrespects Mia's character to do so. DC needs Jason to look ugly because it's harder to empathize with ugly people and it makes it so much clearer who is the bad guy and who is the good one, and it's a much easier dichotomy, so much more comfortable than challenging the whole mythos around which Batman is built. DC needs Barbara to be sexy in their traditional male-gaze way, because this is the audience they're trying to appeal to.
So like, I know that I'm nit-picking when I say "actually according to any and all logic Jason is younger than Tim by a couple of months and than Mia by around three years". Or when I say "they should bring back Dickbabs' old age difference" or even interact with Dickbabs as if they still have that difference and refuse to interact with Tom Taylor's version of the ship. I know comics are incoherent and the timeline is messy; but just because it's messy, just because it's always been, doesn't mean it's innocent. So I'm gonna keep nitpicking, and I'm gonna stay an annoying bitch, because I refuse to allow comics to manipulate me out of my empathy. And because I don't see everything and am very aware of how easy it is to be manipulated even when you're careful, I encourage you to add to this with things you've noticed whether it's in portrayal or in art about character age, appearance, or any other device they might use to manipulate our perception of the characters -and what narrative these resorts serve.