This thread seems to be getting visitors so I will post an update.
I took it to a leather shop and they suggested that it would be way cheaper if I fixed it myself. Per their suggestion I got curved sowing needle set from amazon and used some braided fishing line to fix it. There is a narrow plastic strip behind the lip of the flap that was starting to come undone. Carefully, I sowed back the leather through the original holes in the plastic strip. The strip clips into a metal flat bar in a folded back manner - it's been over 6 months and no issues so far.
Once sown, it does take a little effort to stretch the seat material and clip the plastic strip onto the seat frame underneath. If you have this issue, don't wait too long or the leather will shrink and it will be harder to repair.
What you need:
https://www.amazon.com/dp/B0B3SVK41Z?
Good luck.