  Blazars are a sub-class of quasars with Doppler boosted jets oriented close
to the line of sight, and thus efficient probes of supermassive black hole
growth and their environment, especially at high redshifts. Here we report on
Very Long Baseline Interferometry observations of a blazar J0906+6930 at z =
5.47, which enabled the detection of polarised emission and measurement of jet
proper motion at parsec scales. The observations suggest a less powerful jet
compared with the general blazar population, including lower proper motion and
bulk Lorentz factor. This coupled with a previously inferred high accretion
rate indicate a transition from an accretion radiative power to a jet
mechanical power based transfer of energy and momentum to the surrounding
gas.While alternative scenarios could not be fully ruled out, our results
indicate a possibly nascent jet embedded in and interacting with a dense medium
resulting in a jet bending.
