TLDR: Cenny didn't update my study details two years ago and I still get Youth Allowance without issue. Will I go into debt if I inform them of this?

Hi guys, two years ago I switched my degree from a generic bachelor's to a more specific field under the same faculty. My workload, contact hours, campus, etc. were the exact same, with only the name of my degree having changed. I visited a service centre for help in changing my details, to which they handed me a form and advised I upload it to their website. I did exactly that. Fast forward to today. I've had no hassles with my Youth Allowance at all, and today in just verifying my details, I noticed that they still have me listed as my original bachelor's degree instead of my current one. The form I uploaded is also still accessible, meaning they should have it on their end, and I assume no one has bothered to look at it. In between when I uploaded it and now, I've talked to Centrelink several times and never have they said anything to me.

My question is: If I tell them about this mistake, are they likely to want two years of Youth Allowance back?? There's no way I could pay all that back, and I really don't know how to proceed from here. Thank you.