It'd always been the same: those ugly patches of JavaScript were being added to maintain compatibility with all the browsers... That's why the newest CSS tricks were always out of reach for us
That one is a dud. Most others work for me, though.
explicit border:2px solid var(--border); on the input which takes priority over the class :
.demo-uv-input:user-invalid { border-color: var(--red-muted); background: rgba(239,68,68,.04); }
YMMV but when corrected it works for me on latest Edge, Chrome, Firefox (Windows versions)