In DC time, Jason was about the same age as Tim.
In DC time, Jason 'died' only a few months before Tim took over as Robin.
In DC time, Tim has been Robin for only a few years, tops.
So, Jason should be only a bit older, maybe a year or two, than Tim. Because Tim is only a teenager, Jason also should be a teenager (at best 18 or 19).
So how the hell did Tim age when no one else in the DCU did or does?