  Tidal disruption events (TDEs) occur when a star is destroyed by a
supermassive black hole at the center of a galaxy, temporarily increasing the
accretion rate onto the black hole and producing a bright flare across the
electromagnetic spectrum. Radio observations of TDEs trace outflows and jets
that may be produced. Radio detections of the outflows from TDEs are uncommon,
with only about one third of TDEs discovered to date having published radio
detections. Here we present over two years of comprehensive, multi-radio
frequency monitoring observations of the tidal disruption event AT2019azh taken
with the Very Large Array (VLA) and MeerKAT radio telescopes from approximately
10 days pre-optical peak to 810 days post-optical peak. AT2019azh shows unusual
radio emission for a thermal TDE, as it brightened very slowly over two years,
and showed fluctuations in the synchrotron energy index of the optically thin
synchrotron emission from 450 days post-disruption. Based on the radio
properties, we deduce that the outflow in this event is likely non-relativistic
and could be explained by a spherical outflow arising from self-stream
intersections, or a mildly collimated outflow from accretion onto the
supermassive black hole. This data-set provides a significant contribution to
the observational database of outflows from TDEs, including the earliest radio
detection of a non-relativistic TDE to date, relative to the optical discovery.
