  Isotropic diffuse gamma-ray flux in the PeV energy band is an important tool
for multimessenger tests of models of the origin of high-energy astrophysical
neutrinos and for new-physics searches. So far, this flux has not yet been
observed. Carpet-2 is an air-shower experiment capable of detecting
astrophysical gamma rays with energies above 0.1 PeV. Here we report the upper
limits on the isotropic gamma-ray flux from Carpet-2 data obtained in 1999-2011
and 2018-2022. These results, obtained with the new statistical method based on
the shape of the muon-number distribution, summarize Carpet-2 observations as
the upgraded installation, Carpet-3, starts its operation.
