- Logged-in, user preferences to skin=vector, legacy=on.
- https://test.wikipedia.org/w/index.php?title=Sandbox&action=submit
- {{:25 Ocak}}. Preview.
- {{:Special:PrefixIndex/:}}. Preview.
I suspect a hook somewhere, one that is triggered during rendering/parsing, is causing the skin version to get reset or lost. (Somewhat related to a recent chat at T288857#7331946)