Can't Upload Custom Skin

I recently switched phones and moved over all my data packs/worlds with relative ease. However, as shown in the video, I am unable to upload the skin. The skin is valid and can even be previewed briefly after it claims to have failed. I have uploaded skins multiple times on multiple different devices, so I'm not sure what the issue is. The issue is not the skin file or the method of file upload, both of these things have been thoroughly tested.

Link to exact skin shown in video to prove file is valid: https://www.minecraftskins.com/skin/19439941/dr-poppy