4Bakers
some instances of thumbnails are cropped and some aren't, some are even zoomed in (ie: Beta Portal)
also, it looks like all recent thumbnails have started being downsampled to 800x600, which contradicts the stated 1200x900 ideal resolution.
I think some clearer guides and templates should be in order.
I think safe zones should be overlaid on the in-editor thumbnail capture
I think the SDK control panel tooltips should be updated to reflect the 800x600 resolution change
I think the way thumbnails should be displayed should be more consistent. It's currently really hard to put words on a thumbnail and it not be cut off somewhere (ie: Beta Portal)
Image Gallery
Image 1: VRChat SDK showing "Image Size 1200x900"
Image 2: my browser showing the image is actually 800x600
Image 3: a typical world portal with the default appearance
Image 4: the same world portal with the Beta design. note how the thumbnail is cut off even more than usual, and is stretched horizontally a whole lot.