Hi Ningishzidda
I found a solution, it looks like the problem is in the database, you need to change the values in “Collation”.
I followed this post, step by step, it’s quite easy. (You need to be able to connect to your PhpMyAdmin panel):
https://boringest.blogasian.com/2008/10/how-to-show-chinese-characters-in-wordpress/
I did all this and it worked, the only problem is that I have to re-write all the Chinese part in my site, looks like they got lost with the database update.
Good luck!