If you are affected by this: Drag and drop the task on the workboard from the "wrong" column to the "correct" column.

Upstream: https://we.phorge.it/T15764

This has been reported in T335422 and T160715.

Thus filing a task for potential investigation of the root cause, in case anyone ever finds a reproducer and/or capacity to investigate Phabricator's transaction code.

I wildly guess that a non-default column on a parent board, then moving the task into a milestone, then back to a non-default column on the parent board (milestone columns are displayed on the parent board) play a role here.

Looking into T335422, ignoring the initial task creation, Codex tag, and most recent problem fixing, here's what's in the DB (output manually edited for improved readability):

+---------+----------+---------------------------------------------------------------------------------------------------------+---------------------+
| id      | userName | oldValue and newValue                                                                                   | date                |
+---------+----------+---------------------------------------------------------------------------------------------------------+---------------------+
| 7958421 | ldelench | board:"Design-Systems-Team", fromcolumns:"Requests", column:"Codex Component Backlog"                   | 2022-05-25 21:30:50 |
| 8242869 | ldelench | board:"Design-Systems-Team", fromcolumns:"Codex Component Backlog", column:"Backlog"                    | 2022-09-16 18:15:58 |
| 8483115 | egardner | board:"Design-Systems-Team", fromcolumns:"Backlog", column:"Design-Systems-Product-Roadmap" (milestone) | 2022-12-20 21:52:03 |
| 8483116 | egardner | project: from "Design-Systems-Team" to "Design-Systems-Product-Roadmap" (milestone)                     | 2022-12-20 21:52:03 |
| 8485232 | ldelench | board:"Design-Systems-Product-Roadmap", fromcolumns:"Backlog", column:"Proposed Components"             | 2022-12-21 18:26:50 |
| 8626931 | ldelench | project: from "Design-Systems-Product-Roadmap" (milestone) to "Design-Systems-Team"                     | 2023-02-18 00:41:08 |
| 8664980 | ldelench | board:"Design-Systems-Team", fromcolumns:"Requests", column:"Needs Refinement"                          | 2023-03-03 21:27:53 | <<<
| 8705079 | bmartine | project: from "Design-Systems-Team" to "Design-Systems-Sprint" (milestone)                              | 2023-03-17 13:12:55 |
| 8705081 | bmartine | board:"Design-Systems-Sprint", fromcolumns:"Committed", column:"In Design"                              | 2023-03-17 13:13:40 |
| 8715324 | bmartine | board:"Design-Systems-Sprint", fromcolumns:"In Design", column:"Design Review"                          | 2023-03-21 15:21:37 |
| 8738111 | bmartine | board:"Design-Systems-Sprint", fromcolumns:"Design Review", column:"Ready for Development"              | 2023-03-29 12:38:48 |
| 8803035 | CCiufo-W | board:"Design-Systems-Team", fromcolumns:"Design-Systems-Sprint" (milestone), column:"Refined/Up Next"  | 2023-04-24 21:09:36 | <<<
| 8803036 | CCiufo-W | project: from "Design-Systems-Sprint" (milestone) to "Design-Systems-Team"                              | 2023-04-24 21:09:36 |
+---------+----------+---------------------------------------------------------------------------------------------------------+---------------------+

Underlying DB query, FYI:

SELECT mt.id, u.userName, REPLACE(REPLACE(REPLACE(mt.oldValue,"PHID-PROJ-4gmhqpxrfqgvms2qjyba","Design-Systems-Team"),'PHID-PROJ-6ztp3ghofb4iigying6d','Design-Systems-Product-Roadmap'),'PHID-PROJ-7x2jagmev5l5dyco323o','Design-Systems-Sprint') AS oldValue, REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REPLACE(REGEXP_REPLACE(REGEXP_REPLACE(REGEXP_REPLACE(REPLACE(REPLACE(REPLACE(mt.newValue,"PHID-PROJ-4gmhqpxrfqgvms2qjyba","Design-Systems-Team"),'PHID-PROJ-6ztp3ghofb4iigying6d','Design-Systems-Product-Roadmap'),'PHID-PROJ-7x2jagmev5l5dyco323o','Design-Systems-Sprint'), '\"PHID-TASK-.{20}\",?',''), '\"beforePHIDs\":\\[\\],',''), '\"afterPHIDs\":\\[\\],',''), 'PHID-PCOL-4zzjgyjv7i5nbl63f7lp','Committed'), 'PHID-PCOL-e7a2d7mtre57tqrtgcpk','Needs Refinement'), 'PHID-PCOL-fho6k73fws32xtvnr54a','Ready for Development'), 'PHID-PCOL-ht7qch3vd2ev4noufynl','Backlog'), 'PHID-PCOL-nrq65vsgm6iyxi2c3f2j','Refined/Up Next'), 'PHID-PCOL-o4qolhwlyand4wpv2plw','Backlog'), 'PHID-PCOL-pihiq42brxaubbejuiod','Proposed Components'), 'PHID-PCOL-purybymc2iwhpw26oxss','Design-Systems-Product-Roadmap'), 'PHID-PCOL-rhtndg655bjfbsot54r4','Design-Systems-Sprint'), 'PHID-PCOL-t3bzplilzcmchy74ame6','In Design'), 'PHID-PCOL-v2bi5q3vouwwh7zpqvp5','Requests'), 'PHID-PCOL-vdtqhmojntko7usxjuyj','Codex Component Backlog'), 'PHID-PCOL-wwtuysjejyofumuo7k2m','Design Review') AS newValue, FROM_UNIXTIME(mt.dateCreated) AS date FROM phabricator_maniphest.maniphest_transaction mt INNER JOIN phabricator_user.user u ON mt.authorPHID = u.phid WHERE (mt.transactionType = "core:columns" OR (mt.transactionType = "core:edge" AND mt.newValue LIKE "%PHID-PROJ%")) AND mt.objectPHID = "PHID-TASK-3tlkmmofmuz2vrtn4obq" AND mt.newValue NOT LIKE "%PHID-PROJ-n3w2cazdwjy56gx7ic5b%" AND u.userName != "gerritbot" AND mt.dateCreated < 1682523100 AND mt.dateCreated != 1653525557 ORDER BY mt.dateCreated;