.wp-block-button.icon-after a:after {
  content: "";
  display: inline-block;
  background-image: var(--button-icon);
  background-size: contain;
  width: 24px;
  height: 24px;
  margin-left: 5px;
  background-repeat: no-repeat;
}

.wp-block-button.icon-before a:before {
  content: "";
  display: inline-block;
  background-image: var(--button-icon);
  background-size: contain;
  width: 24px;
  height: 24px;
  margin-right: 5px;
  background-repeat: no-repeat;
}