https://drafts.csswg.org/css-flexbox/#min-size-auto
https://drafts.csswg.org/css-sizing-4/#aspect-ratio-minimum

If an item has an aspect ratio and is a flex item, both specs impose a minimum size on a flex item. Consider:

<div style="display: flex; flex-direction: column; width: 100px;">
  <div style="aspect-ratio: 1/1">
    <div style="height: 500px;"></div>
  </div>
</div>

In this case, the flex item has two constraints:

• Flexbox's automatic minimum size gives it a minimum height of 100px (the transferred size), because it uses the minimum of the content-based size and transferred size.
• aspect-ratio's minimum size gives it a min-height of 500px

What should the used minimum size be? max(100px, 500px)? Or should the flexbox one "override" the aspect-ratio one?

https://github.com/web-platform-tests/wpt/blob/master/css/css-sizing/aspect-ratio/flex-aspect-ratio-026.html relies on the latter interpretation.