The US is rated as an "flawed democracy" and not a "full democracy" for the last decade by the Economist Intelligence Unit (an offshoot of the Magazine that published this article).
First past the post systems generally have lower turnout than proportional systems. Even record turnout for the US isn't very high in international terms.
And if that record turnout is to support and/or oppose a candidate that seeks to burn the whole system down and gets votes due to the system not reflecting voters priorities for a while then it further supports my theory.
Switzerland has usually a less than 50% turnout, for a comparison - and still gets brownie points for democracy. Yes, I'm sad myself, but I'll still take it over any other systems.
A turnout of 63.5% isn't popular? Even compared to past elections it's the second highest turnout in the past 3 decades. The highest was in 2020.