Dashboard search doesn't always match kwargs

[gap777]

We sprinkle metadata into our job kwargs to enable lookup in the Dashboard, like this:

{"ad_id"=>"ad_qTB3kTjQeZEmptyx8JZ5", "ad_ref"=>"A-1012679", "line_item_gid"=>"gid://supply-side-platform/Orders::Types::ReservationLineItem/rli_Dd2LpagvXuqaZNAZt4yu", "purchase_order_id"=>"po_8o9yOwc88sfMQWFmjE8F", "_aj_ruby2_keywords"=>["purchase_order_id", "line_item_gid", "ad_ref", "ad_id"]}

• Searching for po_8o9yOwc88sfMQWFmjE8F finds the job.
• Searching for 8o9yOwc88sfMQWFmjE8F (a substring of the previous arg) finds the job
• Searching for A-1012679 does NOT find the job
• Searching for gid://supply-side-platform/Orders::Types::ReservationLineItem/rli_Dd2LpagvXuqaZNAZt4yu does NOT.
• Searching for rli_Dd2LpagvXuqaZNAZt4yu (a substring of the previous arg) does NOT.

Why can some args (po_8o9yOwc88sfMQWFmjE8F) be used for searching and others (A-1012679) can not be?