Just this week we also saw data from Pfizer & Moderna mRNA vaccine rollouts to frontline healthcare workers in December (at a time of peak infection and emerging variants) that touted 80% effectiveness after a single dose, 90% after two doses. I'm struggling to find a reason not to interpret that as further evidence that the mRNA vaccines are in fact more effective than the J&J shot.
Medical workers take precautions better than the general public, maybe? But they're also far more exposed.