Welp. I didn't get any immediate responses so I continued my looking around and came across
this blog post.
In it, the author states: "...the 1989-1991 Upper Deck cards were often erased by unethical dealers looking to cash in the error craze. I can personally recall being warned specifically about the erased McDonald card back in 1990-91. With little effort, these cards can be erased to show a blank white area on just about any section of the cards, this makes it extremely important to be able to hold a copy and tilt it under a good light source to see if the gloss has been dulled, before purchasing."
So, I took a closer look at my card and, lo and behold, it's been erased. This was more than 25 years ago, but I absolutely do not remember buying this card (or any) at a card shop. I was strictly a kid you bought packs at the corner store.
Sorta disappointing, but such is life. Happy collecting!