Photo Uploading Sideways

I have one horse whose photo keeps uploading sideways and I can't figure out why. The image saved on my computer is oriented the correct way, but when I upload, it gets turned. Can someone help me find a way to stop this from happening?

I found someone with a similar issue here: https://community.etsy.com/t5/Photography-Tips/Photographs-uploadin.../125286474

Apparently it's caused by the way a phone or camera corrects the rotation of an image on its own, but then apparently does not transfer this information when uploading the image.
If you convert your image to jpeg/jpg it should stay in the expected rotation. You can also edit the image in photoshop/paint/etc.. and export to your desired format, after that I assume it should be fine.