I reported two bugs, one is more recent for opening JPG images losing color on the edge and the other is from almost a year ago for random blue tint added to JPG images, but neither has been corrected.
The blue tint is especially annoying. It happens randomly and seems not only when saving an image, but also when opening an image. I think the edge losing color is related to this issue.
Exporting files to PNG works but because of its large size I still have to convert them into JPG. I tried using Mac's own Preview to make the conversion and found out it also randomly adds the blue tint. Then I tried using the GIMP app to convert PNG into JPG and so far it's been working fine.
I hope Pixelmator can fix this issue ASAP.
Is something not working like it should? Let us know.