Dropbox eligibility if visa expired more than 48 months ago

My H1B visa expired in September’2019.

I tried to book my visa appointment on CGI Federal website for December’2023 which makes my visa expired older than 48 months ago.

September’2019 - December’2023 => 51 months

But the confirmation screen after Yes/No questions shows that that I’m eligible for dropbox. Is this correct?

You just need a prior US visa approval in any class but note that IW aka dropbox is at discretion of the consular officer.