Grouping a bunch of misc viz issues that I faced when using MNE:

1. If you do:

epochs.info['bads'] = [epochs.ch_names[0]]
epochs.plot()

it does not show the channel name in gray. Instead it doesn't plot it. This is not technically a bug but inconsistent with what raw.plot() does. I think it would be useful to see the bad channel also in this plot.

2. It would be nice to have a scale also in the epochs.plot as in raw.plot(). It really helps improve the interpretability of the data. this already exists, press s to show it.
3. The scale shown in raw.plot() is incorrect if scalings='auto' since the scale is channel-wise. The scalings/ylim issue seems to be common across multiple viz functions disputed; see below (misc issues with plotting in MNE #8761 (comment)).
4. The vertical green line in epochs.plot() seems to disappear when you scroll to other epochs. addressed in fix epochs vlines #9326
5. In raw.plot_psd the usual matplotlib controls to zoom in, "home button" etc are missing. Not sure if it's only my set up. Happy to share more details if folks can't reproduce easily. addressed in restore MPL toolbar for PSD plots #9331
6. Selecting a channel in evoked.plot() should make the line plot bold so we can see that channel more clearly. I think this is how it used be before. Not sure if there were any reasons to change it? not a regression; see below (misc issues with plotting in MNE #8761 (comment)).