I have never heard anyone claim that previously. Here is the first result I see when I search Google for FANG. It claims that A is Amazon, and that Apple was added later to make it FAANG. https://www.investopedia.com/terms/f/fang-stocks-fb-amzn.asp
You're the first I've heard of. FANG was the original designation for the group of high-growth tech stocks, and the A stood for Amazon. This is pretty well known and verifiable.
Are you sure you didn't just assume the A was for Apple when you read it? I don't know how you could possibly know what people were referring to from the acronym.