It is probably the new screensaver from MacOS sonoma. According to the review on ars technica they are quite large but use purgable storage. Purgable storage is

It is probably the new screensaver from MacOS sonoma. According to the review on ars technica they are quite large but use purgable storage. Purgable storage is a way to keep files on disk but as soon as something else requests the space the purgable files are deleted. https://arstechnica.com/gadgets/2023/09/macos-14-sonoma-the-ars-technica-review/8/ https://arstechnica.com/gadgets/2023/09/macos-14-sonoma-the-...