There’s a comment that may give a little insight on that https://www.bilibili.com/h5/comment/sub?oid=840456272984670275&pageType=17&root=185650169680

Translated with Deepl

(Not great translation, but I don’t know Chinese soooo)

I used to read Mr. Chen’s early microblogging, saying that listening to La San Steel Association heard tears, do not want to be satisfied with the status quo to make money to retire and wait for death, if you do not go to create not to break through, life has no meaning. At that time to see these, to be honest have thought of Mr. Chen will also have to leave hoyomix one day, just did not expect that day to come so fast [aggrieved] thought Mr. Chen is to go in charge of animation project soundtrack, did not think it is to say goodbye [crying] but Mr. Chen may also have their own ideas and pursuit of it, or wish a bright future, and then new heights!

I guess he just wants to move on to something different, though I don’t understand such a decision if it is truly to reach new heights, maybe it is to have more creative freedom? Arguably the reach he got by working on the soundtracks of one of the biggest games of the last few years can never be matched since it is famous worldwide, so I doubt it’s that. Artists get tired too after all