We need to increase contrast in loading spinner slightly as part of UI standardization on these elements.
Base30 #72777d is the color of choice.
There are also small design artefacts which are different than the (new and @Pginer-WMF approved) template.
Change 445424 had a related patch set uploaded (by VolkerE; owner: VolkerE):
[mediawiki/core@master] RCFilters: Standardize loading indicator appearance