I don’t know when this happened, but it was fine in the original 4.0 release.
To set the scene, in case some of this matters, while I was travelling with my laptop I processed some new images in PL4 and exported them with my standard preset that overrides to use one of my watermark presets.
The preset has both an image at bottom left and text at bottom right. The scale on both is set to 5. I noticed that the image was missing but managed to locate a copy and add it back to the watermark, I thought with the same settings it had originally had.
When I exported my images I noticed some seemed to have the image watermark visibly too small. On a landscape photo the two appear consistent in size, but on a portrait photo, the image watermark is obviously small compared to the text.
It’s as if the image is scaled according to the width and the text according to the longest side.
Here are some examples: