Use the following css in the image custom css advanced

/* START clip upper right corner */
selector{
  --cut: 30px;

  clip-path: polygon(
    0 0,
    calc(100% - var(--cut)) 0,
    100% var(--cut),
    100% 100%,
    0 100%
  );
}
/* START clip upper right corner */Code language: CSS (css)