Detected during testing #1503.
Also reproducible @ 9f4afd6 develop
Tested with iPhone 8 plus, iOS 13.1

Reality

• Add media & text block, tap placeholder and choose Choose from device
• Start upload but before it finishes close the post by selecting Update Post
• Reopen the post and wait until the upload finishes
• Result: Low resolution pic is shown
• Open the WP Media library
• Result: Both low and high resolution version of the same image is uploaded

This is happening on Image block as well but it is less noticeable since the cover image has higher resolution.

Expected

• Add media & text block, tap placeholder and choose Choose from device
• Start upload but before it finishes close the post by selecting Update Post
• Reopen the post and wait until the upload finishes
• Verify that high resolution pic is shown
• Open the WP Media library
• Verify that only 1 image is uploaded