“But any idea why that would cause the green shading?”
Don’t know, but generally speaking, max render quality option uses different interpolation, color depth, resampling etc.
For future, when you do export with the same frame size what sequence is (and not using hardware acceleration) you don’t really need max render quality checked, but when resizing to smaller dimensions, you better check it (sharper output). And I’m not sure why you use frame blending when exporting to the same fps.
I would argue with Bill advice as general rule, alhtough it’s ok as work around. When you working not not on loseless or uncompressed, but on compressed sources like mpeg2 or h264, it is not such good idea output to Prores. First, there is conversion to other format, second, there is need for much more disc space for archiving. For compressed formats I would suggest doing masters in the same codec as the source. With fair bitrate (lets say 30%-50% more than source bitrate), there will be no difference in quality (in comparison to prores), but huge difference on gigabytes or simple significant lose of quality if you chose Prores LT for a master clip. I did some tests of Prores variables on 1080p h264 material, and my conclusion was, that only Prores 444 is reliable to maintain quality of the source, and Prores HQ is good for less quality demanding outputs (so is good for most of my work to be honest).