Explaining the difference between excess deaths and covid-19 deaths is staggeringly easy: governments are lying and obfuscating the number of covid-19 deaths on a massive scale, as expected and predicted by everyone who knows anything about how governments report preventable deaths.

Making out that simple, obvious, things are "mysterious" and "nuanced" is a lie. When the first-order understanding covers 90% of the reality, you report it as such.

https://theconversation.com/covid-19-deaths-in-the-us-continue-to-be-undercounted-research-shows-despite-claims-of-overcounts-198266