Often tools that value files over apps brag about supporting markdown - it's a very common file format for most text+ applications. However, not all markdowns are created equally.
Technically, the original spec for Markdown was defined here: https://daringfireball.net/projects/markdown/syntax - however you'd be surprised to see that there's actually a number of features that most markdown supporting apps add-on on top of the basic spec.
These enhancements are great! However it also means that not all features that work in one application will work in another, and sometimes they may have conflicting parsing rules / definitions for what symbols should do what when rendered.