I am sure that only a few days ago I was able to make a horizontal image flip … did something change? I can not find the function on the recent version.
Manjaro/Arch/git version
The buttons to flip and rotate 90deg are in the ‘orientation’ module - I don’t think anything has changed there recently. If for some reason you don’t see the module, try searching for it in the ‘search modules by name’ box.