In reply to Joost de Valk.

First I've heard of it. In fact, my PR was based on another PR which was based on another PR which was based off of a plugin:

https://github.com/sortabrilliant/guidepost

(And it still took almost a year after I created my PR for the block to become polished enough to merge. 😛)

I never saw the Yoast SEO table of contents block mentioned in https://github.com/WordPress/gutenberg/issues/11047 or any of the Gutenberg PRs ...in fact, I didn't even know Yoast had a table of contents block.