I have that sometimes... think of something interesting to write, start think about words I would use, and topics/tangents I would go on, and then when I sit down to write, all inspiration disappears and I'm left with a post idea and no idea what I was gonna say about it.
I also have 'unposted dust'... I have several blogs saved as drafts, which I saved to write about later and already added the pics (pictures usually help to tell my stories), and now its been so long that I no longer know what I'm going to write about them, and those drafts are sat there gathering dust!
some of them are from 2023... oops!