I'm sure there are some misdiagnoses, but enough to skew the results in any significant way? I'd bet $1000 to $1 that the number of unreported cases caused by covid-19 exceeds the number of misattributions that were caused by something else.
Not to mention misattributions in the other direction - e.g California's discovery of earlier cases, and subsequent backdating or earliest known case.
The attacks on counting likely/suspected cases reek of motivated reasoning
So seeing as total cases are likely underestimated and total deaths are likely overestimated, the 1% hardly seems to me to be the lower floor.