Which method is responsible for displaying thumbnails in Mediawiki?

Question

CMS

Task: to replace on the fly the address of the image source from the local address to the external one.
That is, the thumbnails are stored on an external server, already generated and warm, only the domain differs in the address, it remains only to change it.
We are looking for a method, function or piece of Mediawiki code that is responsible for displaying thumbnails and images in order to change it as needed.