[Image description: text which says "You're a 10 but it's on the pH scale". Underneath is a picture of a woman whose face suggests she is dropping hard truths. OP has since learned that this is a character from a show saying "You're basic" and that the post is accidentally self-referential]
The joke here is that a pH of 10 is considered basic (as in the opposite of acidic), and the character at the bottom is calling someone basic (as in the devastating human insult). The current alt text does not allude to that connection in any way.
Fixed
i'm fairly sure Lally is sharing and didn't create the original meme. if it was that critical to the joke, the OP should have added in the caption from that frame of the show. If they did, I'm sure Lally would have included it in the alt text. As it is, a lot of people who see the meme without the aid of alt text might not get that part of the joke, so the alt text is doing a fine job of describing the image as it is.
Oh, my comment was not criticizing the alt text or anything. I just wanted to add additional context.
fair! i guess i'm just saying, often when i am doing alt text, i feel a pressure from the community to get the name of every character and media reference correct, even if i am not familiar with the referenced media. I'm not sure what the correct way is to indicate that you aren't trying to be critical, but I'm just putting that out there as a thing to be mindful of.