Search Kit doesn't display related contact custom fields
If you have a Search Kit that includes a related contact, displaying the related contact's custom data will actually show the main contact's custom data.
See screenshots below. Teresa has a most important issue of "Education", Santina's is "Social Justice". When I build a search and include both the
Constituent Information: Most Important Issue and
Contact Related Contacts: Constituent Information: Most Important Issue columns, they both have the same value.