In other major Mastodon apps, the content warning gets preserved when replying to someone else's toot. Here, only replies to one's own toots with CW get tagged with that CW as well.

In case this is intended: One could argue that replies don't necessarily require the same content warning, so one could just add the appropriate CW manually - but I think that mostly, the same CW still applies. Also, it's way quicker to remove it than to re-add it from before.