Can't read mailbox (spinner running continuously) Incorrect string value in oc_mail_recipients

Steps to reproduce

1. Create new blank nextcloud instance using docker-compose(https://github.com/nextcloud/docker/blob/master/.examples/docker-compose/insecure/mariadb/apache/docker-compose.yml)
2. Configure mail app to fetch my existing email account (which seems to have an email causing with an incorrect character in mail_recipients)
3. viewing the inbox

Expected behavior

inbox should show existing emails like it works for other folders like "junks" of the same email account

Actual behavior

When viewing the inbox, no emails will be shown and spinner running continuously
Following error is shown in the log:
OCA\Mail\Exception\ServiceException: Sync failed for 1:INBOX: An exception occurred while executing a query: SQLSTATE[22007]: Invalid datetime format: 1366 Incorrect string value: '\xC3' for column nextcloud.oc_mail_recipients.label at row 1

Mail app version

3.0.2

Mailserver or service

gmx

Operating system

ubuntu 2204 with docker

PHP engine version

PHP 8.1

Web server

Apache (supported)

Database

MariaDB

Additional info

I also see this problem on my "production" nextcloud instance version 25 and mail 2.2.4 using the same email account

As far I could see utf8mb4 is enable in the config.php I could find mysql.utf8mb4' => true

Thanks for any help
best regards
Jochen

Recreate the issue with the linked docker-compose setup and inspect the sync log for the SQLSTATE error involving oc_mail_recipients.label. Compare the MariaDB encoding with the mysql.utf8mb4 setting in config.php and verify the inbox can display the existing messages without the continuous spinner.