Why does the same photo or video that I receive in iMessages show up in different resolutions on my iPhone and my iPads?

This has been bugging me for quite some time, and I haven’t been able to figure out why.

Here’s an example. Just today my sister sent me a one-minute video taken on her 12-inch iPad Pro.

When I looked at it on either my iPad Pro or iPad Mini, the resolution was horrible.

When I saved it, here’s the info about the resolution and file size:

But when I went to my iPhone, it was a much higher resolution with the following specs:

(I was able to download/save the second one by choosing to save a ‘duplicate’.)

Could someone please tell me what I’m doing wrong here? TIA!

Interesting! What about the version you got on Messages on the Mac? If the results were reversed (small on the iPhone, large on the iPad), I might have suggested that it was trying to save bandwidth via cellular.

Alas! also low resolution on the Mac.

???

Sounds like some testing with other videos might be in order to see if there are commonalities or differences to be observed.