The sidebar says
This community is the place to discuss and ask questions about anime, anime news, and related topics
Emphasis mine. Episode discussions are created here constantly, so what’s the problem with linking a full legal episode of an anime?
The idea that if it was a trailer it would be fine is ridiculous
Getting into what is or isn’t anime can be thorny sometimes. The rule of thumb I follow, which I have mentioned in the past, is that if a show/movie has either a MAL or AniList page, then it is relevant enough for this community. AniList includes donghua in their database, including this show, so it is fine to post about.
What this discussion has made me realize though, is that the bot wasn’t tracking donghua like it does anime. The AniList api includes it, but I was filtering to just the JP shows. So, I will be removing that filter going forward. I apologize retroactively to all the donghua fans out there that didn’t have a place to talk about it.