textarea使用auto-height,在真机显示时下方为何出现大量空白?

<view class="section--text">资讯：</view>

<textarea

class="section--elem" name="title" maxlength="600" auto-height="{{true}}" value="{{title}}" placeholder="前24个字元将纳入标题使用 | 支持多行" placeholder-style="color: #d3d3d4" bindblur="bindTextAreaBlur" bindinput="bindKeyInput"></textarea>

</view>

bindTextAreaBlur: function (e) {

this.setData({

title: e.detail.value

})

},

bindKeyInput: function(e) {

let str = e.detail.value;

this.setData({

title: str

});

},