Test site: https://seirdy.one/2020/11/23/website-best-practices.html
Mirror with compatible cipher suites: https://envs.net/~seirdy/2020/11/23/website-best-practices.html

Several <blockquote> elements on that page are enclosed by <figure> elements, with <figcaption> elements at the bottom of the figures containing attribution:

<figure>
  <blockquote>
    There is only one honest measure of web performance: the time from when you click a link to when you’ve finished skipping the last ad.
  </blockquote>
  <figcaption>
    — Maciej Cegłowski, The Website Obesity Crisis
  </figcaption>
</figure>

However, the SerenityOS browser tends to render figures with the caption at the top of the figure:

This doesn't seem to happen for all figures, only the ones with short captions.

Source order, DOM order, and display order should generally match unless CSS alters the display order (bad practice but valid) or JS alters the display or DOM order.