  The neutron star low-mass X-ray binary SWIFT J1749.4-2807 is the only known
eclipsing accreting millisecond X-ray pulsar. In this manuscript we perform a
spectral characterization of the system throughout its 2021, two-week-long
outburst, analyzing 11 NICER observations and quasi-simultaneous XMM-Newton and
NuSTAR single observations at the outburst peak. The broadband spectrum is
well-modeled with a black body component with a temperature of $\sim$0.6 keV,
most likely consistent with a hot spot on the neutron star surface, and a
Comptonisation spectrum with power-law index $\Gamma \sim 1.9$, arising from a
hot corona at $\sim$12 keV. No direct emission from the disc was found,
possibly due to it being too cool. A high truncation radius for the disc, i.e.,
at $\sim$20--30 R$_{G}$ , was obtained from the analysis of the broadened
profile of the Fe line in the reflection component. The significant detection
of a blue-shifted Fe XXVI absorption line at $\sim$7 keV indicates weakly
relativistic X-ray disc winds, which are typically absent in the hard state of
X-ray binaries. By comparing the low flux observed during the outburst and the
one expected in a conservative mass-transfer, we conclude that mass-transfer in
the system is highly non-conservative, as also suggested by the wind detection.
Finally, using the Nicer spectra alone, we followed the system while it was
fading to quiescence. During the outburst decay, as the spectral shape
hardened, the hot spot on the neutron star surface cooled down and shrank, a
trend which could be consistent with the pure power-law spectrum observed
during quiescence.
