This is my first post and I want to thank the Affinity Designer team for the amazing program.
I spent over 10 hours last week with the latest released version (non-beta) extensively comparing Bilinear, Bicubic and Lanczos3 resampling methods. I shrank and enlarged different images using each resampling method, exported them to PNG, and compared them side by side in FastStone. It was extremely tedious. When I saw that Preview was added to Export in Designer I immediately downloaded the Beta.
The fact that the Preview window is not maximizable to full screen is nothing short of ridiculous for the awesome program Designer is. It almost renders the feature useless. Yes you can zoom and pan, but the window is insultingly too small. I also see the narrower aspect ratio reported above.