text.onPath, and the Design panel's Put text on path button that runs
it, kept the text layer's own fill and effects when the text went onto
a path. The help center's Guide to text says that the vector object's
fill and effects are transferred to the text layer.
The text now takes the path layer's fills, with their fill style and
variable bindings, when one of them shows, and the path layer's effects,
with their effect style and bindings, when it has any. The text's own
bindings on those fields are dropped. When the path has no visible fill
or no effects, the text keeps its own.