  We studied the electronic Raman spectra of (Li$_{1-x}$Fe$_x$)OHFeSe as a
function of light polarization and temperature. In the B$_{1g}$ spectra alone
we observe the redistribution of spectral weight expected for a superconductor
and two well-resolved peaks below T$_c$. The nearly resolution-limited peak at
110 cm$^{-1}$ (13.6 meV) is identified as a collective mode. The peak at 190
cm$^{-1}$ (23.6 meV) is presumably another collective mode since the line is
symmetric and its energy is significantly below the gap energy observed by
single-particle spectroscopies. Given the experimental band structure of
(Li$_{1-x}$Fe$_x$)OHFeSe, the most plausible explanations include conventional
spin-fluctuation pairing between the electron bands and the incipient hole band
and pairing between the hybridized electron bands. The absence of gap features
in A$_{1g}$ and B$_{2g}$ symmetry favors the second case. Thus, in spite of
various differences between the pnictides and chalcogenides, this Letter
demonstrates the proximity of pairing states and the importance of band
structure effects in the Fe-based compounds.
