space wrongly added near `<sub></sub>` in sidebar

[njzjz]

Describe the bug

In the sidebar, extra space is added near <sub></sub>:

But the title looks fine:

I expect the sidebar looks like the title.

Reproduce the bug

The markdown file is

# The thermal decomposition of CL-20 (C<sub>6</sub>H<sub>6</sub>N<sub>12</sub>O<sub>12</sub>)

List your environment

No response

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