Hello everyone
I wanted to update my post:
I went to the Dior store and showed my bag. The SA checked the handles and explained what we can do about it.
Normally after checking the invoice info, they are taking photos and sending them to France HQ to decide if it is caused by the customer or it is some kind of manufacturing defect.
If it is the customer's fault they are offering to fix it with their cobbler with or without a fee (depending on the fixing issue)
If it is a manufacturing defect they are sending the old bag to France HQ and giving you a brand new one!
SA thinks my problem might be caused by hand sanitizer (maybe the previous owner of the bag held the handles after using hand sanitizer, but I didn't) and even though I don't have an invoice or the previous owner's name she still offered to fix it with their cobbler. Dior's customer service is the best I must say

Now I'm waiting my bag to be fixed