I have seen the SN cards where it is in marker rather than the gold numbers. .
If your card was one of those one card per box 1/1 than it likely is not fake since it was likely sealed and packaged by Topps. If you purchased the card from ebay, well that could be a different story and probably isn't genuine.
Basically, if you bought it off of ebay or any site where random people list cards, it has a high chance of being fake. If you bought it from a sealed box, it is likely real and not fake, like this card in the article below.
https://www.beckett.com/news/pat-nesheks-2018-topps-heritage-shohei-ohtani-autograph-sells-for-over-6000/
Hope I could be of help.
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