If you plot (exponentially growing) cases or deaths against time, you’ll get a straight line on a log-linear graph (as here). If you make both axes logarithmic,

If you plot (exponentially growing) cases or deaths against time, you’ll get a straight line on a log-linear graph (as here). If you make both axes logarithmic, you get an exponential curve again (but squished). Maybe you’re thinking of the double log curve of total cases vs new cases that was on HN recently.