Load a custom image

I do not like the images that use your plugin, I would like to insert a default image for each new registration, the member can change his avatar if he does not like the default avatar. I try with the code below in bp-custom but it does not work:

function kawaii_default_avatar_url() {
    return 'https://example.com/avatar.jpg';
}
add_filter( 'bp_core_default_avatar_user', 'kawaii_default_avatar_url' );