Garage Ceiling Drywall

Is there any problem using exterior drywall for a garage ceiling? I saw this in a house today. The drywall appears to be 5/8" but I have never seen exterior drywall used for a garage ceiling before. Is there any problems with this that you might be aware of. I am unsable to reference specifically exterior drywall for use in garage ceiling. Any help would be appreciated.

Check with the manufacturer if it is USG it should say firecore on it they do make the stuff for the drive throughs on buildings they have to be fire rated if a car starts on fire under one of them

Exterior Gypsum Sheathing is available in a 1/2" thick, 2’ wide with a tongue and groove edge or, 1/2" & 5/8" thick, 4’ wide square edge product.5/8" Exterior Gypsum Sheathing has a Type X core, for use in fire rated assemblies.