By default, Google slides uses "Smart quotes" (the quotes that look "cooler" because they detect where you need the opening-looking quote and where you need the closing-looking quote).
The issue is I was making slides with code in them. Since it's code, I needed the quotes to be normal quotes, so that I can easily copy and paste into a code editor.
How to turn off smart quotes on Google slides
Go to the "Tools" tab and click "preferences.
Uncheck "Use smart quotes".
That's it. You should no longer have those fancy smart quotes.