Per @Volker_E's note on T280666#7087963 - the colour #4A4F53 should be removed from the 'newspaper' icon as it's not a defined colour in the palette. The navigation menu item (not part of the newcomer features) which should just use the same icon colours as the rest of the mobile side nav, which is Base20 or #54595d.
icon in question with incorrect colour is the newpaper icon for the "Main page" nav item