@m455 short answer: nope.

the main part of the article, the points from the gist by the Grid, a hostile fork by a very toxic developer, has things that were never true, and many things that were fixed since then (as addressed in https://www.matrix.org/blog/2019/09/27/privacy-improvements-in-synapse-1-4-and-riot-1-4 for example). But yet they refuse to update their gist with the current state, instead choosing to perpetuate so much FUD, causing new blogs like this to be written (and shared) as well.

the rest is mostly a bunch of dubious claims ending with "but we haven't actually investigated this" (because then you'd find out it's not true)