The HTTP Working Group of IETF published a working draft HTTP Client Hints to defines a set of HTTP request header fields, which documented the Save-Data header to tell the server that the client need to reduce data usage. This header is suitable for mobile devices that accessing satellite internet.
See: https://tools.ietf.org/html/draft-ietf-httpbis-client-hints-04#section-3.5
A browser extension is available for test.
https://www.ctrl.blog/entry/http-save-data

In case of receiving Save-Data header, the MediaWiki server should activate a compressing mechanism to reduce the size of audios, images and videos, then send to the client.

https://nooshu.github.io/blog/2019/09/01/speeding-up-the-web-with-save-data-header/

It is also exposed to JavaScript for use in any client-side decisions.

if ( 'connection' in navigator && navigator.connection.saveData === true ) {
    // …
}