We found what I think is a bug in Preact's hydration. By default, if Preact finds HTML comments during the hydration, it removes them. The problem is that while doing so, it also recreates (removes and adds again) the next DOM node.

I've reproduced the issue in this repository: https://github.com/luisherranz/preact-comments-hydration-bug

I've also checked it in Preact's own tests, and it's also happening there: luisherranz/preact@004d25b

I've recorded a video to show the repository and tests:

https://www.loom.com/share/89dbe2ac14164bb9a35457cd27e10cce