Using revealOrder="backwards" in SuspenseList only works for very short wait times

I realize that this is still experimental, but I figured it would still be good to report bugs. If not, feel free to close this issue.

I was playing around with the examples in https://reactjs.org/docs/concurrent-mode-patterns.html#suspenselist and noticed that revealOrder="backwards" didn't seem to work. The trivia items never appear before the posts. After fiddling around with the example in https://codesandbox.io/s/black-wind-byilt i noticed that it works if the timeout is set around 500 ms or below for the trivia items. But if you set it to for example 1000 ms, it will instead wait until both trivia and posts are available.

revealOrder="forwards" seems to work regardless of how long the timeout is.

I tried changing React version to the latest experimental version (0.0.0-experimental-c76e4dbbc-20210722), but it did not seem to make a difference.

重現 React 文件和連結的 CodeSandbox 中的 SuspenseList 範例，比較 revealOrder="backwards" 在 500 ms 和 1000 ms trivia 延遲下的表現。首先檢查回報的 experimental React 版本以及範例的 timeout 行為；完成的標準是找出原因，並修正或明確處理較長等待時間下的 backwards 順序行為。