This is not posted by the artist. This is simply a picture of several clearfiles that they have.
The clearfile at the forefront was drawn by sen and dates back to at least 2012: https://www.suruga-ya.jp/product/detail/994908593
Image on the right: Miku Symphone 2018-2019 TOWER RECORDS A4 clearfile illustrated by Tama.
https://wmg.jp/hatsune-miku-symphony/news/83133/
Third-party tweet with closeup
Image on the left: Illustrated by hakusai mute. A special clearfile that came as a bonus for an album by Asa of Yoshiwara Lament.
https://jp.mercari.com/item/m61024241474
Updated