You're right. As written, it looks like it's saying:
I learned some facts about him today like
- his favorite color;
- green, his favorite food;
- pizza, and what he wanted to be when he grew up;
- a teacher.
The style guides I've looked at list two uses of a semicolon:
- Separating multiple independent clauses, as a pause that's weaker than a period, but stronger than a comma.
- Separating items in a list, when doing so with a comma would be confusing, because some of the items in the list contain commas.
Neither one of those is happening here; instead, the author has used a semicolon between a description (such as "his favorite color") and its corresponding identification ("green"). That's not one of the accepted uses of a semicolon.
One option would be to just switch the commas and semicolons:
I learned some facts about him today like his favorite color, green; his favorite food, pizza; and what he wanted to be when he grew up, a teacher.
But I'd probably use parentheses instead:
I learned some facts about him today like his favorite color (green), his favorite food (pizza), and what he wanted to be when he grew up (a teacher).