  It has been claimed in [arXiv:2110.09522] that the expression for the Sagnac
coordinate time delay given in [arXiv:2109.14641] "differs from the standard
interpretation described in the book by Landau-Lifshitz (LL)". We note that: 1)
the Sagnac effect is not even discussed in LL; 2) the expression in
[arXiv:2109.14641] is standard, given in countless papers and even textbooks;
3) the expression by LL quoted by the author consists of the (infinitesimal)
two-way trip travel time for a light signal, which the author confuses with the
Sagnac time delay (when they are actually very different things); 4) such
confusion would negate the existence, both in special and general relativity,
of the well-known and experimentally tested Sagnac effect; 5) the claims that
it sheds doubt in any of the assertions made in [arXiv:2109.14641] are
completely unfounded.
