Upon inspection, I think sunligh676919 is a third-party source. I've found multiple instances of the twitter posting official art (ex from ch 57 of Lanxi Zhen) and other people's fanart (ex which is post #7759463) without any sort of marking by way of source. That said, for this particular image I wasn't able to find the original artist. Similarly, the account has tweeted other images for which I haven't been able to find a better source (eg google says this image was once on this page but I scrolled as far as I could and it doesn't seem to be there anymore).