  It has been suggested that late-universe dark matter decays can alleviate the
tension between measurements of $H_0$ in the local universe and its value
inferred from cosmic microwave background fluctuations. It has been suggested
that decaying dark matter can potentially account for this discrepancy as it
reshuffles the energy density between matter and radiation and as a result
allows dark energy to become dominant at earlier times. In this work, we show
that the low multipole amplitude of the cosmic microwave background anisotropy
power spectrum severely constrains the feasibility of late-time decays as a
solution to the $H_0$ tension.
