Is Intensity Non-Uniformity Correction (N4BiasFieldCorrection) performed by default in fmriprep?

The methods section of my visual quality assessment report states that INU was performed using N4BiasFieldCorrection was performed prior to brain extraction in the structural image. However, I couldn’t find a mention of this step in the documentation -https://fmriprep.readthedocs.io/en/stable/usage.html

Is this step being performed by default?

Yes, it is part of the brain extraction workflow.