The behavior of sqfr depends on the value of ratvars,
but the user documentation doesn't say that it does.
So this should be a bug report, but I think it would be
better to give sqfr an optional second argument
that does what ratvars does. I've included
a proposed new sqfr function
C1) display2d : false$
(C2) p : expand((x-a)*(x-b)*(x-y^2))$