Element UI version

2.15.10

OS/Browsers version

Chrome/107.0.0.0

Vue version

2.7.13

Reproduction Link

https://codepen.io/MrtianYs/pen/QWxdgWL

Steps to reproduce

1.初始化头尾两列不显示
2.mounted中两秒后显示头尾两列

What is Expected?

自定义单元格内容显示正确

What is actually happening?

第三列的自定义内容被显示显示在了第二列