Changing assignee of a task leads to status change

When changing an assignee of a task assigned to me which is currently in Todo state the state is automatically changed to On hold.

E.g. happened here

(Manually changed status to Backlog after this happened)

_{Huly®: UBERF-8882}

No source file or test is named in the report. Start by reproducing the issue by changing the assignee of a Todo task and observing the status change, then trace the TypeScript task-assignment and status-update entry points. Done means changing the assignee leaves the task in Todo, with a regression test covering the case.

Written by the indexing model from the issue text.