  We present the discovery of J22564-5910, a new type of hot subdwarf (sdB)
which shows evidence of gas present in the system and has shallow, multi-peaked
hydrogen and helium lines which vary in shape over time. All observational
evidence points towards J22564-5910 being observed very shortly after the
merger phase that formed it. Using high-resolution, high signal-to-noise
spectroscopy, combined with multi-band photometry, Gaia astrometry, and TESS
light curves, we aim to interpret these unusual spectral features. The
photometry, spectra and light curves are all analyzed, and their results are
combined in order to support our interpretation of the observations: the likely
presence of a magnetic field combined with gas features around the sdB. Based
on the triple-peaked H lines, the magnetic field strength is estimated and, by
using the shellspec code, qualitative models of gas configurations are fitted
to the observations. All observations can either be explained by a magnetic
field of ~650 kG which enables the formation of a centrifugal magnetosphere, or
a non-magnetic hot subdwarf surrounded by a circumstellar gas disk/torus. Both
scenarios are not mutually exclusive and both can be explained by a recent
merger. J22564-5910 is the first object of its kind. It is a rapidly spinning
sdB with gas still present in the system. It is the first post-merger star
observed this early after the merger event, and as such is very valuable system
to test merger theories. If the magnetic field can be confirmed, it is not only
the first magnetic sdB, but it hosts the strongest magnetic field ever found in
a pre-white dwarf object. Thus, it could represent the long-sought for
immediate ancestor of strongly magnetic WDs.
