Observable dropped the “beta.” subdomain, so you might need to update your user style domain:
@-moz-document domain("observablehq.com") {
div[id][data-node-id]:before {
content: attr(id);
position: absolute;
right: calc(100% + 20px);
top: 5px;
pointer-events: none;
z-index: 1;
}
}