Hi,
I'm getting the same Symptom with the stainless steel appearance. Its happening in a lot of drawings and across hundreds of files and so far just ignored it.
If i have to switch appearance to steel that would be a pain.
The issue seems like there is a slight difference in scaling on the visible edges compared to the shaded model that revolves around the view origin (or some arbitrary) point as across the view the difference gets worse. *speculation* Perhaps an old scaling factor hard coded as a hack fix for something else that has since been changed and since.
It seems to be especially bad in views created from a storyboard in the animation workspace ( as shown in the picture )(I tend to use iso & shaded views more in this way so take this difference with a grain of salt) but also happens from design, as with OP. Also same as OP it only happens in isometric views and not in ortho or section views. Also it seems that the scaling happens in the "model coordinates" as smaller parts have a less noticeable offset around the edges, even when scaled to be the same size on the page.
large assembly has significant scaling top of this view the edges seem to align and it gets worse as you go down.
this is a smaller part of the model and it shows no or not noticeable edge alignment issues.
This is in Fusion 2.0.19440 x86_64
Best of luck with this issue.
Thanks