After hours of research and tests, I finally managed to fix the encoding of a database after it was imported on another server. Usually an export from a server works on another server even if the database charset is different, but it seems this bug causes the issue.
This was the post that contains the right solution for this problem.
In case this link is no more available, I included the solution below:
#!/bin/bash -e
DB_HOST="$1"
DB_USER="$2"
DB_PASSWORD="$3"
DB_NAME="$4"
mysqldump -h "$DB_HOST -u "$DB_USER" -p"$DB_PASSWORD" --opt --quote-names \
--skip-set-charset --default-character-set=latin1 "$DB_NAME" > /tmp/$DB_NAME.sql
mysql -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD" \
--default-character-set=utf8 "$DB_NAME" < /tmp/$DB_NAME.sql