Per PageImages phab project description.

A null edit does fix it.

The data shown by the popups can be seen on https://es.wikipedia.org/api/rest_v1/page/summary/Jorge_Guillermo_I_de_Brandeburgo (kept broken on purpose)

The template was first vandalized on 2023-01-28 05:02 UTC, with reverts back and forth until 2023-01-28 06:13.

We would need to invalidate the caches that had been rendered in that timeframe for pages using ficha de persona.

After some scanning, out of 270975 articles using ficha de persona, only 264 have that bad image (< 0.1%).

In T328880#8588148, @Platonides wrote:

A null edit does fix it.

The data shown by the popups can be seen on https://es.wikipedia.org/api/rest_v1/page/summary/Jorge_Guillermo_I_de_Brandeburgo (kept broken on purpose)

The template was first vandalized on 2023-01-28 05:02 UTC, with reverts back and forth until 2023-01-28 06:13.

We would need to invalidate the caches that had been rendered in that timeframe for pages using ficha de persona.

We did do a null edit on that template. Sadly it seems we still have some objects that weren't properly cleared from cache. So there is an additional bug on top of T271184#8585977 I would say. The null edit to the template solved the issue for a few test pages I used.

Cache should be cleared now for the rest of the pages.

Could someone document how the cache is cleared here so that in case of a more severe abuse any sysadmin could just do it?

We send a null edit to the template that regenerated the summary endpoint pages that transclude it.
In case of a single page, a purge event or a purge action would also trigger a pregeneration on the APIs.