:deep usage as a combinator has been deprecated. Use :deep(<inner-selector>) instead of :deep <inner-selector>.

根据提供的引用内容，:deep用作组合器已被弃用。现在应该使用:deep(<inner-selector>)代替:deep <inner-selector>。

以下是一个示例，演示如何使用:deep(<inner-selector>)来替代:deep <inner-selector>：

/* 使用:deep(<inner-selector>) */
.parent :deep(.child) {
  color: red;
}

/* 替代使用:deep <inner-selector> */
.parent /deep/ .child {
  color: red;
}

请注意，:deep(<inner-selector>)和/deep/ .child都是用来选择.parent元素下的.child元素，并将其颜色设置为红色。