Extracted from T278894: [1.37] The class mw-ajax-loader will no longer be styled by Vector for Wikibase.

The legacy feature of ResourceLoaderSkinModule will be deprecated in the 1.36 release (see T89981)

In the 1.37 release Vector will drop use of the legacy feature. This will reduce the amount of bytes on the critical path of Vector.

This will also remove styling support for the elements .mw-ajax-loader, .mw-small-spinner
https://codesearch.wmcloud.org/deployed/?q=(mw-ajax-loader%7Cmw-small-spinner)&i=nope&files=&excludeFiles=&repos=

Repos that wish to continue to use these styles should either

1. copy across the style to their own repository. It would be preferable if such repos used their own class as well to avoid false positives in the above search result.
2. Use $.createSpinner() from the 'jquery.spinner' library.

Acceptance Criteria🏕️🌟

• We no longer directly use the deprecated class that will be removed in the future