I have a very large Anki collection which I have
been maintaining for the last 3 years(not on this email).
The last few weeks I had the feeling that cards where previously
there were images on it did not have them anymore.
Yesterday I reviewed a card where I am absolutely certain it had images, I did not have any and I do not mean the missing image sign, the entire image has been removed from the file.
I searched all cards and could not find the image, checking my media I found many unused images.
I deleted all of them, the next day there were more unused images even though I had deleted no cards.
I am not sure if it is my memory that is failing or the anki system bugging out. If necessary I can share all data.