Yep
Nah. Too man arbitrary assumptions.
I assumed that abnormal size has to do with it being a PNG instead of a JPEG, as is normally used for large photo-type images.
But I'll big into it.
That's because screen caps are record far fewer pixels. This thing is 1125x2436 at 16bit.
Remember that PNG images are essentially bitmaps under lossless ZIP-like compression. That's not very good for photographic images.