The HTML spec contains a list of [special rules for H1 tags](https://html.spec.whatwg.org/multipage/rendering.html#sections-and-headings) nested within `article`, `aside`, `nav`, or `section` tags. Chrome 140 deprecates these special rules, because they can cause accessibility issues. For example, they can visually reduce the font size for nested `h1` tags so that they look like `h2` tags, but nothing in the accessibility tree reflects this demotion.
The current behavior is an accessibility problem: the font size is reduced as if an <h2> is being used, but the a11y tree still shows the item as an <h1>. By removing these special rules, we'll nudge developers to do the "better" thing of actually using an <h2>.
Docs: https://github.com/whatwg/html/issues/7867#issue-1218728578