The spacing between the headline and the first reference depends on the bibliography style and may be not consistent with other sectioning commands in the document.
A quick way to modify it is to add some spacing to the hook executed at the beginning of the list of references. This hook is controlled by the command
\AtBeginBibliography, so adding something like
in the preamble should do what you want.
10pt to fit to your document class settings (use a negative value if you want to reduce the spacing).
In the example below I've exaggerated with
90pt just to show that it works.