Why special characters like = or " break PHP regexp when using \b word boundary?

Question

this is a follow up after reading How to specify "Space or end of string" and "space or start of string"?

From there, it states means to match a word

Answer 1

" is, of course, not special.

The word boundary, \b, OTOH, is. It looks for a word beginning/ending, and on the boundary it expects a word character - and the quote is not such a character.

Remove it from the end or replace it with a negative look-ahead search for a word character.