Attribute mapping problem

[Spencer Thomas]

Running SP 3.4.0, an IdP is sending (in part) this attribute:

            <saml2:Attribute FriendlyName="urn:oid:1.3.6.1.4.1.5923.1.1.1.9"
                             Name="urn:oid:1.3.6.1.4.1.5923.1.1.1.9"
                             NameFormat="urn:oasis:names:tc:SAML:2.0:attrname-format:basic"
                             >
                <saml2:AttributeValue xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance
                                      xsi:type="xs:string"
                                      >staff at college.edu</saml2:AttributeValue>
            </saml2:Attribute>

Our attribute-map.xml file has (in part) this mapping:
    <Attribute name="urn:oid:1.3.6.1.4.1.5923.1.1.1.9" id="eduPersonScopedAffiliation">
        <AttributeDecoder xsi:type="ScopedAttributeDecoder" caseSensitive="false"/>
    </Attribute>

And I see this error in the shibd log

2023-02-03 20:08:11 INFO Shibboleth.AttributeExtractor.XML [12] [default]: skipping SAML 2.0 Attribute with Name: urn:oid:1.3.6.1.4.1.5923.1.1.1.9, Format:urn:oasis:names:tc:SAML:2.0:attrname-format:basic

What can I advise the IdP owner to change, and/or what can I change to accept this value? I note that we have lots of other IdPs sending this attribute without problem, although I do not have the exact XML for those IdPs. In this case, the IdP maintainer sent us the attribute XML as logged at his end.
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