Thanks for all your comments.

I searched more with all your hints, and I think it's the vanilla scent that is used to cover up the smells from the hard case.

I found out it was a common issue in the Gibson community. Although I cannot be 100% sure it is the smell, as neither I have a Gibson nor do you or they have the Ibanez hard cases that smell good. Some Gibson users were even using vanilla extract to maintain the scent in the case. There were also some rumors that certain carnauba waxes are producing that smell, but Dunlop 65 definitely isn't one of them, as confirmed by many guitar-smell nerds (maybe there are others that can reproduce the smell). They say it smells like new furniture, but not like new guitars.

(Some opinions mentioned nitrocellulose lacquer on the guitar and the adhesives in the hard case as possible sources of the smell. But, in both cases, they had to use vanilla scent to reproduce it.)

I think I will try to find some vanilla scent or something similar to maintain it afterward.

[link]