You can divest yourself of your ignorance on Adobe Illustrator anytime you want to.
If you believe the certificate is fake, do you think that the Governor of Hawaii and Director of Health and State Registrar are all in on it?
I use Adobe Creative Suite every day. A PDF is a document format, a file type. It can have layers. It can have vectors. It can be a flattened uneditable document. It can be RGB, it can be CMYK, it can be grayscale, etcetera etcetera. Attempting to ascertain or condemn the accuracy of any content of a PDF by means of the manner in which the file was saved is meaningless. A PDF, again, is merely a document file type, one of many. It is not automatically a scan of anything and it is not “fake” or a “forgery” if it isn’t. It’s not automatically authentic or valid if is a scan. This whole thing is a fool’s errand. It is what it is, independent of the factuality of any representation it may appear to make.