String <s/'s> in H1 element creates strikethrough of several elements throughout the book

[MichSpieler]

Description

A user reported seeing strikethrough in text formatting where none was applied.

This could be traced back to a string that appears repeatedly in a chapter: <s/'s> (in the visual editor, in the text editor displayed as <s/’s>). This only seems to create an issue if the string appears inside an H1 element. If the apostrophe/single quote in the string is deleted, the strikethrough effect disappears. Escaping the apostrophe/single quote (replacing it in the text editor with &39; did not resolve the problem as upon leaving the text editor, the string &39; was converted into a apostrophe/single quote '

Steps to Reproduce

1. Create an H1 in a chapter
2. Add the string <s/'s> to it
3. Save and view the chapter

Expected behavior:
The string is displayed without any effect on other text in the book.

Actual behavior:
Strikethrough is applied to many elements.

[MichSpieler]

Removing the apostrophe (that is not escaped in the text editor) from the string solves the problem. The apostrophe alone does not create an issue.

[MichSpieler]

The user who reported this has removed the < and > characters from the H1 element as a work around.

[MichSpieler]

This is the source code of the chapter's page (in my testbook). It has a <s> element before the main element. This element appears in other chapters as well.