It was pointed out in T88397 that a list=search query was populating the
'redirecttitle' output property as an object containing the internal
members of a MediaWiki Title object, where a string containing the prefixed
title is more likely what was intended.
Any clients relying on this output property should be updated to deal with
the corrected value.
This will be deployed to WMF wikis with 1.25wmf16, see
for the schedule.
Brad Jorsch (Anomie)