• Check if updating to the latest Preact version resolves the issue

Describe the bug
In JSX under , Preact creates <ins>/<del> inside <mi> in the MathML namespace, so they don’t render. HTML + MathML requires these to be HTML namespace phrasing elements.

To Reproduce
Preact REPL: Preact REPL
JSFiddle: https://jsfiddle.net/3e460jvw/

Expected behavior
Children like <ins>/<del> under <mi> are created in HTML namespace and render.

When the MathML token elements (mi, mo, mn, ms, and mtext) are descendants of HTML elements, they may contain phrasing content elements from the HTML namespace.

Spec: https://html.spec.whatwg.org/multipage/embedded-content-other.html#mathml
https://w3c.github.io/mathml-core/#token-elements