User icon Garbled characters

While building NextCloud at home, a problem arose that could not be solved, so support was needed.
In my environment, except for ver25.04, the text in the user icon is □ (Japanese only) all the time.
I would like to solve this, but is it possible?
In addition, the DB is set to utf8mb4, and the environment in the Nextcloud application is
It is set to Japanese and only the icon is □.
The environment is as follows. I’ve already tried it in a few environments.
almaLinux 8.6/ 9.2、RockyLinux,Ubuntu22.04
PHP 8.0 to 8.2
mariaDB 10.3/10.6
NextCloud 25.0.4 to 27.1.2

Due to the fact that most people in Europe are not using a Japanese desktop, it might help if you could provide an example which characters you are using and what hex code is behind it.
As far as I remember someone posted a request to support Chinese characters some days ago. It seems that it has already been picked-up and a pull request has been created to get the avatar creation fixed. It might solve your issue too?!

Thank you for your reply