MicroSoft - and likely others - decided they knew more about life than users. so when using/viewing using stuff like "File Explorer" - images would 'auto rotate' and appear "right" on your computer display. but, the images were not 'right' - so when 'uploaded' various software packages would read/honor/use the header data to display 'on the Forum' in the orientation as per header data.
yep. didn't always work.
and . . . in everyone's defense . . . if you clicked on a pix, it display one way.... if you looked at the pix in 'File explorer' it (may) appear differently. a click on 'Rotate Left' or 'Rotate Right' would fix it.
but heh serious