Non-UTF-8 encoding detected. This may cause issues with accented or special characters

Hello, I'm having an issue since updating to LibreSign 11.1.2.

In the LibreSign system info, I see the following warning:

Status | Message | Resource | Hint
info | Non-UTF-8 encoding detected. This may cause issues with accented or special characters | java | Ensure the system encoding is UTF-8. You can check it using: locale charmap

When signing, if the signer's name contains special characters (such as accents), they are replaced with question marks (?).

Here is the output of my locale command:

root@nextcloud:~# locale
LANG=fr_BE.UTF-8
LANGUAGE=
LC_CTYPE="fr_BE.UTF-8"
LC_NUMERIC="fr_BE.UTF-8"
LC_TIME="fr_BE.UTF-8"
LC_COLLATE="fr_BE.UTF-8"
LC_MONETARY="fr_BE.UTF-8"
LC_MESSAGES="fr_BE.UTF-8"
LC_PAPER="fr_BE.UTF-8"
LC_NAME="fr_BE.UTF-8"
LC_ADDRESS="fr_BE.UTF-8"
LC_TELEPHONE="fr_BE.UTF-8"
LC_MEASUREMENT="fr_BE.UTF-8"
LC_IDENTIFICATION="fr_BE.UTF-8"
LC_ALL=fr_BE.UTF-8

I'm running Nextcloud Hub 10 (31.0.3).

Do you know what might be causing this issue, even though my system is configured in UTF-8?

Thanks in advance!

Start with the LibreSign system info warning, the reported locale output, and the signing flow where accented signer names become question marks. Reproduce the problem with the provided UTF-8 environment and determine whether the Java resource or PHP integration changes the encoding. Done means accented and special characters remain intact and the warning correctly reflects the system encoding.