Underscore in title doesn't get properly escaped for pdflatex build target, causing formatting errors

[VolkerH]

Describe the bug

context

When I build a book using builder pdflatex, and the book title contains and underscore _ character, it appears that the underscore character doesn't get properly escaped and is interpreted by LaTeX as an indication that the next character is a subscript.

Here is a cropped screenshot from a book called Using redactedprocess_client showing the title page. This formatting error is repeated throughout the header of each page.

expectation

The _ is part of the title and should be rendered as an underscore rather then be interpreted as a subscript marker.

Reproduce the bug

1. Use a tiltle such as Using jupyter_book_somthing
2. Build the book using --builder pdflatex

List your environment

Jupyter Book      : 0.15.1
External ToC      : 0.3.1
MyST-Parser       : 0.18.1
MyST-NB           : 0.17.2
Sphinx Book Theme : 1.0.1
Jupyter-Cache     : 0.6.1
NbClient          : 0.7.4

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