I use the first wave of COVID-19 as a natural experiment to document evidence of flexibility on the German day-ahead electricity market. I parameterize a model that represents uncertainty on the demand side as intermittency of renewables. I then compare pre- to post-COVID-19 data to investigate lower-bound economic implications. Post-COVID-19and with 44% of renewable shares, electricity prices were most sensitive to fuel costs, and almost completely passed through, while they remained rigid to CO2 costs. A decrease in demand consumption had a detrimental welfare effect on both, consumers and producers. An increase in demand consumption was slightly beneficial in the afternoon peak, mainlyfor consumers. Although the distributional gap was reduced, both actors, were worst off post-COVID-19. This kind of flexibility response was likely the result of a reduction in the minimum generation. CO2 emissions were lower by 22% on average, of which emissions from lignite showed only a small reduction of 8% of total emissions from fossil fuels. If the observed consumption pattern persists to some extent, in a market with higher renewable shares and more extreme weather conditions, more appropriate market rules would be necessary to achieve allocative efficiency.