[Bug] When the content contains two font sizes, the toolbar font size is displayed incorrectly

[oumomomo]

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• [X] Is this really a problem?
• [X] I have searched the Github Issues for similar issues, but did not find anything.

Affected packages and versions

dev

Reproduction link

操作步骤： 1、输入内容，将内容前半段字号设置为72号，后半段字号设置为20号 2、在72号字号区域输入内容，再回到后半段输入内容 3、观察工具栏字号

Expected behavior

在前半段输入内容再回到后半段输入，工具栏展示为后半段的20号

Actual behavior

在前半段输入内容再回到后半段输入，工具栏展示为72号

https://github.com/dream-num/univer/assets/167171356/053f8afb-6331-422f-b639-26f73a886c61

System information

No response