That’s the whole point. It will delete things if there’s not enough space. I don’t have a whole lot of games but if you watch a couple of 4K movies, look at your iCloud Photo Library, play some Apple Music, etc. it’s going to delete some screensavers and then re-download them again later. The more space you have then the fewer things need to be deleted.
None of the tasks you list use up space on the Apple TV 4k. 4k movies are streamed and not stored, photos are kept in the cloud and not stored in memory. Music is streamed and not stored. Therefore nothing you list will result in the deletion of screensavers.
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