markr66942480, thank you for providing the sample file. It always makes researching these issues so much easier. I took a look and my guess is that your alpha interpretation isn't set to premultiplied on one system, but it is on the other. Could you select the source in question and in the Project Panel right click on it and choose Modify > Interpret Footage. How is the alpha interpretation set? If you change it to explicitly be Premultiplied does the issue go away - it does on my system. I'm a bit surprised that this changed after updating as I don't know of a reason why that would be the case. I wonder if deleting your media cache would resolve this for you?
As above, this is just an alpha interpretation issue. The file itself is rather odd - it's rendered on a red background rather than black. Thus, if the alpha channel turned off completely, you'll see the white artwork on red. (Clearly visible in the Dropbox online viewer.)
In Quicktime Player, or in AE or Premiere with straight alpha interpretation, you get a red fringe.
So there may indeed be a change in the way the updated applications interpret alpha channels by default, but there's no actual rendering error here. Just ensure your QT files have the interpretation set to Premultiplied and they will look fine.
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