数据结构如下：
diversionParamList: [
{
length: null,
positionNumber: null,
value: null,
}
]

思路：可根据 index 动态绑定 :props 属性值，校验规则写在:rules

<div class="config-item" v-for="(item, index) in form.diversionParamList" :key="index">
  <el-form-item :label="`分流配置${index + 1}`" :prop="`diversionParamList.${index}.positionNumber`"
    :rules="{ required: true, message: '请输入位置', trigger: 'blur' }">
    <span class="config-item-text">位置：</span>
    <el-input-number size="small" style="width: 100px" v-model="item.positionNumber" :min="0"></el-input-number>
  </el-form-item>
  <el-form-item :prop="`diversionParamList.${index}.length`"
    :rules="{ required: true, message: '请输入长度', trigger: 'blur' }">
    <span class="config-item-text">长度：</span>
    <el-input-number size="small" style="width: 100px" v-model="item.length" :min="1"></el-input-number>
  </el-form-item>
  <el-form-item :prop="`diversionParamList.${index}.value`"
    :rules="[{ required: true, message: '请输入值', trigger: 'blur' }, { pattern: /^[0-9A-Fa-f]+$/, message: '必须是1-9或16进制字符:a-f或A-F' }]">
    <span class="config-item-text">值：</span>
    <el-input :maxlength="item.length * 2" v-model="item.value" placeholder="请输入值" style="width: 150px">
      <template #prefix>0x&nbsp;</template>
    </el-input>
  </el-form-item>

  <div class="button-group">
    <el-button v-if="index === form.diversionParamList.length - 1" type="primary" size="small"
      @click="addFormConfig()">新增
    </el-button>
    <el-button v-if="index !== 0" type="danger" size="small" @click="delFormConfig(index)">删除
    </el-button>
  </div>
</div>