  We present results from a five-month-long observing campaign of the unusual
transient AT 2022fnm, which displays properties common to both luminous red
novae (LRNe) and intermediate-luminosity red transients (ILRTs). Although its
photometric evolution is broadly consistent with that of LRNe, no second peak
is apparent in its light curve, and its spectral properties are more
reminiscent of ILRTs. It has a fairly rapid rise time of 5.3$\pm$1.5 d,
reaching a peak absolute magnitude of $-12.7\pm$0.1 (in the ATLAS $o$ band). We
find some evidence for circumstellar interaction, and a near-infrared excess
becomes apparent at approximately +100 d after discovery. We attribute this to
a dust echo. Finally, from an analytical diffusion toy model, we attempted to
reproduce the pseudo-bolometric light curve and find that a mass of $\sim$4
M$_\odot$ is needed. Overall, the characteristics of AT 2022fnm are consistent
with a weak stellar eruption or an explosion reminiscent of low-energy type IIP
supernovae, which is compatible with expectations for ILRTs.
