On your PC, flip it 360° and save it again under a new name. Your OS uses different image orientation information than browsers do. This way you can overwrite it.
I meant what I said. it "looks" like before, but when you save it, you'll overwrite the orientation info that the browser is reading with the the ones the OS is reading.
It's because whatever app you are using to flip it is not removing the EXIF metadata, which the camera saves into the file. This contains data about what position the camera was in when the picture was taken. Some websites or apps use this data to flip the image when it's displayed. So if you want to have it right side up when you flip it, you either need a app that removes the EXIF, or one that modifies it.
Shot from my iphone, downloaded from Google Photos via Firefox on Windows 11, created this post using Firefox. I tried flipping it with Windows photo viewer earlier. I'll upload it to Imgur first since it strips Exif.
Weird. Our image upload process isn't doing anything special to the images that I'm aware of. I downloaded the image from above and on my PC flipped it:
I compared the version I saved from Beehaw to the version I downloaded through Google. Beehaw definitely stripped the EXIF data, but I think it was still reading from it before I posted.