I doubt 0.65% death rate. Perhaps 0.65% of what has been REPORTED/TESTED. Do we really know how many folks had mild symptoms or asymptomatic that never were tested? I’ve seen reports/estimates it may be 10-30x as many.
No, the Case Fatality Rate (CFR) is 2.7%. That comes from 224,732 deaths and 8,388,038 identified cases in the US. The Infection Fatality Rate is the actual underlying mortality rate. It's the ratio of deaths independent of missed cases and deaths. By March/April, we knew it was between 0.5% and 1%. By the end of May, every new study had it between 0.64% and 0.66%. There have been literally dozens of studies confirming the IFR at 0.65% which is why the CDC publishes that as the overall IFR (Source).
"Do we really know how many folks had mild symptoms or asymptomatic that never were tested?"
Yes, we do. You take a combination of serology studies performed in multiple regions, combine it with excess mortality figures, and cross check that with the documented stats on asymptomatic/mildly symptomatic/moderately symptomatic/severely symptomatic cases from blanket testing protocols (e.g. hospitals, where everyone gets tested regularly regardless of symptoms) and you build a solid profile of how many have been infected.
In the US, around 12-13% of the population has been or currently is infected. That varies significantly by region. For example, in New Jersey that's closer to 29% whereas Utah is closer to 3%.