Why is Lightroom (cloud based) slightly cropping my RAW images on import? I can see I lose about 1% of image compared to when opened in windows file explorer

When I view the RAW image in file explorer through the open with ‘photos’ option, and I compare the same image to what has been imported into Lightroom, I can see I have lost a very small amount of the image (perhaps 1% of each side of the image). I have searched the web for about 3 hours now and found no reason why this might be, or any solution. Just to clarify- I don’t have any ‘Optics’ settings on, like Lens Correction that changes the image on import. The image is also in full and no crop has been applied.

The only have two camera and this issue is there for both- Panasonic GX80, and an older Nikon D200- The Nikon D200 is the camera I noticed this issue with, and the issue is worse on this camera than the Panasonic (it’s so so slight on the Panasonic and really takes some zooming in to see that’s it happening- but it’s still there!. The cameras are set to their full aspect ratio.

I don’t understand why this is happening, and it’s obviously quite upsetting that Lightroom is removing a part of my image, and has been for a while without me knowing.

Any help would be very much appreciated

Tom