Illegal mix of collations

I am managing a MariaDB 10.6 Server for a bunch of people. I also dump the databases for backup purposes. Recently, one of the databases started to make problems while dumping: > mysqldump: Couldn't execute 'show create table my_view': Illegal mix of collations (utf8mb4_general_ci,COERCIBLE) and (utf8mb4_unicode_ci,COERCIBLE) for operation '=' (1267) Everything in that database was created using the utf8mb4 character set and utf8mb4_unicode_ci collation. I checked the DB, tables, columns and view. I then found out, that when I open a regular mariadb shell, the collation_connection differs:

MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE "collation_connection";
+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8mb4_unicode_ci |
+----------------------+--------------------+
1 row in set (0.002 sec)

MariaDB [(none)]> SHOW VARIABLES LIKE "collation_connection";
+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8mb4_general_ci |
+----------------------+--------------------+
1 row in set (0.003 sec)

**My first question:** Why does the global scope have a different collation_connection compared to the session scope? I always thought the session scope inherits from the global scope. I was not able to find in the docs, where this gets set. Here are the relevant parts of my mariadb option file:

[mariadb]
character_set_server=utf8mb4
collation_server=utf8mb4_unicode_ci

[client]
default-character-set=utf8mb4

[mariadb-dump]
default-character-set=utf8mb4

**My second question:** How to prevent such issues? Do I have to tell all of my users to use the same collation to prevent issues like that? --- Here is an example to reproduce it:

CREATE TABLE employees (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    department VARCHAR(100),
    salary DECIMAL(10, 2),
    created_at TIMESTAMP
);

INSERT INTO employees (name, department, salary, created_at)
VALUES
    ('Alice', 'HR', 50000, NOW()),
    ('Bob', 'Engineering', 70000, NOW()),
    ('Charlie', 'HR', 45000, NOW()),
    ('David', 'Engineering', 80000, NOW()),
    ('Eve', 'Marketing', 60000, NOW());

SET collation_connection = utf8mb4_unicode_ci;

CREATE VIEW hr_employees AS
SELECT id, name, salary
FROM employees
WHERE department = 'HR' AND date_format(created_at, "%Y") IN ('2024');

SET collation_connection = utf8mb4_general_ci;

SHOW CREATE VIEW hr_employees;
ERROR 1267 (HY000): Illegal mix of collations (utf8mb4_general_ci,COERCIBLE) and (utf8mb4_unicode_ci,COERCIBLE) for operation '='