Pictures taken from mobile phones may appear rotated on webpages.
This may be because desktop browsers and mobile phones interpret metadata differently.
These issues may occur when you take pictures with your smartphone sideways.
Sometimes, even though you take a picture with your phone sideways, mobile phones can still correctly judge which side of the picture should be up. But desktops may not be able to do this. This could be one of the reasons pictures taken with mobile phones may appear rotated when placed into webpages. I recently ran into this issue with pictures taken using Apple's iPhone 11 Pro mobile phone. The way I fixed it was to use Microsoft Paint on a desktop computer to rotate the picture in reverse (relative to the way the picture was displaying in webpages) and then save and then re-upload to my website. (So the picture now was displaying rotated 90 degrees when opened using Microsoft Paint on my desktop, but displays correctly when this picture is uploaded to my website.) My website is Linux based and hosted by Godaddy.