  Recent measurements and analyses from the Dark Energy Spectroscopic
Instrument (DESI) Collaboration and supernova surveys combined with cosmic
microwave background (CMB) observations, indicate that the dark energy density
changes over time. Here we explore the possibility that the dark energy density
is constant, but that the cosmological recombination history differs
substantially from that in $\Lambda$CDM. When we free up the ionization
history, but otherwise assume the standard cosmological model, we find the
combination of CMB and DESI data prefer i) early recombination qualitatively
similar to models with small-scale clumping, ii) a value of $H_0$ consistent
with the estimate from the SH0ES Collaboration at the $2\sigma$ level, and iii)
a higher CMB lensing power, which takes pressure off of otherwise tight
constraints on the sum of neutrino masses. Our work provides additional
motivation for finding physical models that lead to the small-scale clumping
that can theoretically explain the ionization history preferred by DESI and CMB
data.
