The unit of the "Spectrum" subplot in the ICA properties figure

When calling ICA.plot_properties(), the ordinate of the subplot titled "Spectrum" is labeled "AU^2/Hz (dB)":

(taken from https://mne.tools/stable/auto_tutorials/preprocessing/40_artifact_correction_ica.html#looking-at-the-ica-solution)

• Why "AU" and not the unit of the sensor type (e.g., µV for EEG)?
• dB here means – what? That the plotted value is 10 log10 (AU^2/Hz)?
• Why is the subplot titled "Spectrum" and not "PSD"? Seems inconsistent with our naming elsewhere?

A comparable figure produced by EEGLAB looks like this:

(taken from https://eeglab.org/tutorials/08_Plot_data/Plotting_ICA_components.html)

Or am I reading this wrong?

I feel that the axis label there makes it much clearer to understand what's being shown.

Start at the ICA.plot_properties() entry point and inspect how the "Spectrum" subplot and its ordinate label are produced. Compare the displayed quantity and units with the documentation example and related PSD plots; done means the title and axis label accurately describe the plotted values for the supported sensor types.