Unknown 1875-A 5 Franc French Proof

My friend consigned this coin to Heritage and they set it off to NGC for slabbing. It came back as an unknown proof. Could it be an essai?

(I found a 5 centimes coin of the same year, which NGC designated as an essai, and it didn't have the word “ESSAI” on the coin.)

https://coins.ha.com/itm/france/republic-proof-5-francs-1875-a-pr65-ngc-/p/3115-124001.s?ic2=mytracked-lotspage-lotlinks-12202013&tab=MyTrackedLots-101116

Hello 🤖

Without pictures, it will be very difficult for anyone to help you. Could you please post clear pictures of each side of your item?

Please note that this is an automatic message. Feel free to ignore if it is not relevant.

Impressive!

Heritage fairly gushes over it. 

Bonne chance!