Comment by SebastianFrelle

I think the level of transparency on display here is really inspiring. I'd apply that same level of candor in a meeting with a peer or a higher-up and basically tell them that you are dissatisfied with the quality of the work that you deliver.

A good manager or colleague will be really receptive towards that kind of openness. They'll be able to help you cut through the "bs" so to speak and help you separate impostor syndrome noise from actionable facts.