First, you need to break the multivalue field into separate entries
This is one way to do it:
| makemv delim="," product_category
| mvexpand product_category
| stats values(product_category) as vpc dc(product_category) as dpc count by user_id
from User warren – Stack Overflow https://stackoverflow.com/questions/76386274/get-statistical-distribution-of-multivalue-entry-in-splunk/76400300#76400300
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