  We report a mathematical error and a misinterpretation in arXiv:2103.03263v4
[Phys. Rev. Lett. 127, 193901 (2021)] that has led to a debate about the nature
of the transverse orbital angular momentum (OAM) of spatiotemporal optical
vortices (STOVs). The transverse OAM of STOVs evaluated theoretically in that
Letter is actually only the intrinsic contribution, while the operators used to
evaluate the intrinsic and extrinsic contributions are not Hermitian operators
as they may lead to complex-valued expectation values.
