Inside this triple-quoted string, in a python buffer:

a = """This is a test"""

python-mode yields (python-info-triple-quoted-string-p)=t, whereas python-ts-mode gives nil, defeating the fancy doc string folding both modes implement.

The reason seems to be that (syntax-ppss) returns something different in position 3 (which is "non-nil if inside a string”) between these modes: 

t for python-mode (which signals a triple quote)
 ?34=" in python-ts-mode 

If you first load python-mode, then load python-ts-mode, the syntax parse becomes equal between the modes, and this bug vanishes.  

python.el v0.28, Emacs v29.1