error 20 when adding entry: Duplicate value rejected for multi value attribute (with unique-attribute plugin DISABLED (default)!)

[gudtanha2]

LDAP: error code 20 - The provided LDAP attribute mobile contains duplicate values

Default 00-core.ldif is in use, which defines

attributeTypes: ( 0.9.2342.19200300.100.1.41
NAME ( 'mobile' 'mobileTelephoneNumber' ) EQUALITY telephoneNumberMatch
SUBSTR telephoneNumberSubstringsMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.50
X-ORIGIN 'RFC 4524' )

So this is a multi value attribute.

Plugin : Type : enabled
-----------------------------------:---------------------------------:--------
...
UID Unique Attribute : unique-attribute : false

The UID Unique Attribute is disabled.

Nevertheless this operation fails:

May 19 00:00:00 - ERROR - Error while adding entry cn=exampleuser,ou=EXAMPLE,ou=People,dc=example,dc=com in directory :javax.naming.directory.AttributeInUseException: [LDAP: error code 20 - The provided LDAP attribute mobile contains duplicate values]; remaining name 'cn=exampleuser,ou=EXAMPLE,ou=People'
May 19 00:00:02 - ERROR - Error while synchronizing ID cn=exampleuser,ou=EXAMPLE,ou=People,dc=example,dc=com: java.lang.Exception: Technical problem while applying modifications to the destination
# Tue May 19 00:00:00
dn: cn=exampleuser,ou=EXAMPLE,ou=People,dc=example,dc=com
changetype: add
employeenumber: n/a
gender: M
telephonenumber: +0123456789
mail: redacted
....
objectclass: inetOrgPerson
objectclass: organizationalPerson
objectclass: person
objectclass: top
registrationauthority: 1
uid: 0000000
...
ou: EXAMPLE
mobile: +1-234-567890
mobile: +1-234/567890
cn: exampleuser
...

Expected Behaviour
Entry will be added (like our previous LDAP server (389-ds) accepts this)

Additional context
OpenDJ 4.10.2 on RHEL9,.7

Am I missing a global directive?

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