1/ I'd put this historically. "Gold OA" originally meant OA delivered by journals regardless of the journal's business model. Both fee-based and no-fee OA journals were gold, as opposed to "green OA", which meant OA delivered by repositories. https://twitter.com/aarontay/status/1379136333705211904

2/ Over time, some referred to fee-based gold as "gold" without qualification. That was sloppy, like referring to complex carbs as "carbs" without qualification. Sometimes we need adjectives to resolve ambiguity.

3/ Complex carbs are carbs. But "carbs" (without a qualifying adjective) doesn't unambiguously denote complex carbs. Sloppiness would become error if "carbs" came to mean complex carbs alone & exclude simple carbs. This is what happened to "gold OA". Sloppiness became error.

4/ As this sloppiness and error became more common, the meaning of "gold OA" drifted. Many who didn't know the original meaning thought "gold" positively excluded no-fee OA journals, contradicting the original concept.

5/ I accept that meanings change as usage changes, even when usage changes because of sloppiness or misunderstanding. (I'm a descriptivist.) I don't insist that "silly" must still means "blessed" just because it once did.

6/ I understand why some people are confused. We're in the middle of a period of drift. The drift of "silly" is over. But (for example) we're still living through the drift of "enormity" to include "enormousness", which causes confusion.

7/ I'm torn. I fought sloppiness and error about "gold" in the name of precision. However, I know that at some point it's useless (and silly) to deny the reality of drift. But have we reached that point?

8/ To me, it's still worth fighting the drift of "literally" to include "figuratively". It's new enough to be sloppy and wrong. But we should accept the drift of "silly" to exclude "blessed" because usage has settled. However, the drift of "gold OA" is neither so new nor so old.

9/ I have no problem using the term "diamond" for no-fee OA. "Diamond" never meant both fee-based and no-fee. But "gold" did once mean both, and to many people still does.

10/ The term "open access" underwent similar drift. It originally meant access free of both price & permission barriers. But early on many used it to mean access free of price barriers alone. I introduced the gratis/libre terms in 2008 to enable precision.
https://dash.harvard.edu/handle/1/4322580

11/ In the case of "open access" we generally succeeded in reversing the regrettable drift (which in 2008 I thought was unwinnable). Today most people realize OA means removing both price and permission barriers. Can we reverse the drift of "gold OA"?

12/ If you do want to push back against the drift: (1) Use "gold OA" to mean OA delivered by journals regardless of the j's business model. (2) Don't call APC-based OA "gold" w/o qualification. Call them "fee-based or "APC-based" OA. Or "fee-based" or "APC-based" gold.

13/ For the record, there are good reasons to avoid the term "gold" for general audiences, apart from drift & ambiguity. It's not self-explanatory; it's positively opaque. Same for "green", "diamond", "platinum", "bronze". They're insider jargon, like the tech terms in any field.