Reproduction steps:
1. Open Unity project in "New Unity Project.zip (64.6 KB) "
2. Select "New Sprite Atlas" in the Project window
3. Inspect preview in Inspector window
4. Delete the atlas and create a new Sprite Atlas (new Atlas will also be named "New Sprite Atlas")
5. Select "New Sprite Atlas" just created
6. Inspect the preview in the Inspector window

Expected result: The preview is empty because there are no Sprites packed, if the cache is stored in relation to asset name, then all cache associated with the asset should be removed during the asset deletion
Actual result: The preview from the previously deleted Atlas is still visible until the new Atlas is re-packed

Reproducible with: 2018.4.28f1, 2019.4.12f1, 2020.1.9f1, 2020.2.0b7 (2D Sprite 1.0.0)
Could not test with 2021.1 because 2D Sprite was no available

Notes:
1. Atlas name must be the same
2. In Unity 2020.2.0a15 and higher you will need to install the "2D Sprite" package to create Sprite Atlases
3. A video is attached
4. 2D sprite was not available in 2021.1