The changes to the figure dpi in a903315 makes the figure in the notebook backend larger and more fuzzy. Presumably because the size of the figure is not set correctly in the nbagg backend and the figure ends up being rescaled to the same default display dpi

Edit:

The actual issue is just that the figures are now larger because we increased the DPI.
The actual figure size in the notebook is in pixels so that the figure size in pixels will be dpi * figsize_in_inches exactly as is should be however the figure is subjectively to large