GNU FreeFont (FreeSerif, FreeSans), as shipped with MuseScore Studio.

These fonts are licensed under the GNU General Public License version 3
with the following font exception:

As a special exception, if you create a document which uses this font, and
embed this font or unaltered portions of this font into the document, this
font does not by itself cause the resulting document to be covered by the
GNU General Public License. This exception does not however invalidate any
other reasons why the document might be covered by the GNU General Public
License. If you modify this font, you may extend this exception to your
version of the font, but you are not obligated to do so. If you do not wish
to do so, delete this exception statement from your version.
