Vertical image taken on smartphone "gets" horizontal when uploading

Question

I arrived here after trying to understand and look for some solution, but this is one of the rare times I can say that I have no idea what to do. It is a small real estate system (the image is of a toilet). The photo was taken from a smartphone and is normal on the computer (standing). By clicking to upload, it becomes horizontal (in this case I’m using Jcrop to upload).

I’d have some idea of what might cause it?