I write a considerable amount of markdown these days, but I've developed a numbering style that is deliberately not part of the syntax.
(1) Foo.
Bar.
(2) Baz.
Auto (re-)numbering can be really surprising, and numbered sections tend to be narrower and harder to read.
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One cute feature of markdown I'd not noticed before: there's no syntax for images *without* a description (i.e. alt text).

https://spec.commonmark.org/0.31.2/#images
It's odd how lazy evaluation is generally seen as a niche design choice, yet the vast majority of languages treat `foo() || bar()` as short-circuiting.
When a tool supports both regular expressions and literal strings, which should be the default?
If you default to regex, users can match more strings than they realise (e.g. `foo.txt`) or less (e.g. `foo(bar)`).
I typically see regex as the default, but I prefer the opposite.