…I am curious if you think the problem lies in the mounting hole or if you feel the perimeter of the saw itself is not concentric.
I messed with shims between the back face and arbor washer but never could make much improvement in the cutting teeth runout. It looks like the mounting hole and rear surface are quite true, but the front edge with teeth is just a bit wobbly relative to the mounting surface.
This is a Lenox, $18 from Amazon.
It worked reasonably well when cutting. I’m sure an annular cutter would be great but, for the money and intended use here, the home saw works. The arbor did seem to help things stay rigid and true as possible.