.yoast-labeled-inserter {
    position: relative;
    width: 100%;
}
.yoast-labeled-inserter::before {
    content: attr(data-label);
    position: absolute;
    left: 0;
    height: 100%;
    color: black;
}
.yoast-labeled-inserter > .block-editor-inserter {
    width: 100%;
}