Welcome to Microsoft Q&A platform and thanks for posting your question here.
From your question, I understand that you have manually uploaded an image file with dimensions of 1080 x 1080 pixels. Following this, you initiated the creation of a snapshot and are attempting to download one of these snapshots, which is displayed as an icon.
If this is the scenario, are you downloading the correct snapshot? You can use the tool Azure Storage Explorerto upload the snapshot and download the correct one. (Right-click on the file for which you took the snapshot and view the snapshot).
A snapshot of a blob is identical to its base blob, except that the blob URI has a DateTime value appended to the blob URI to indicate the time at which the snapshot was taken.
Hope this helps. If you still have questions, please let us know in the "comments" and we would be happy to help you. Comment is the fastest way of notifying the experts.
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Thanks