Been loving 10.x.x thus far, thanks for all of your hard work! I did stumble on something today, however:

When a component renders two sibling elements (A which is dynamic and B which is static), preact produces DOM in the incorrect order if A renders null before later rendering content. I don't think it matters, but in case it does: the static sibling (B) does not have to be a component, i.e. you can replace <B /> with the literal <p>B</p> and the issue will still repro.

Some details:

• This issue does not repro on any 8.x.x version. It does repro on every 10.x.x version, including alphas and betas.
• I tested the dynamic component using both hooks and classes, and the issue occurs in both flavors.

/** @jsx h */
import { h, render } from "preact";
import { useState, useEffect } from "preact/hooks";

const A = () => {
  const [show, setShow] = useState(false);
  useEffect(() => {
    setTimeout(() => setShow(true), 1000);
  }, []);

  // intentionally render <div> instead of <p> to ensure the root elements
  // of both components are different, in case that changes any behavior.
  // The issue of course repros even if a <p> is used.
  return show ? <div>A</div> : null; 
};
const B = () => <p>B</p>;

render(
  <div>
    <A />
    <B />
  </div>,
  document.body
);

// Expected:
<div>
  <div>A</div>
  <p>B</p>
</div>

// Actual:
<div>
  <p>B</p>
  <div>A</div>
</div>

Link to sandboxes with minimal repro:

• Using classes: https://codesandbox.io/s/preactorderingissue-xtjs3
• Using hooks (same as above snippet): https://codesandbox.io/s/preactorderingissuehooks-s62ch