There is a need to include special characters including square brackets for password validation.
Password validation is done by the below script OOB:
Out of the box code the below regex to verify the password strength:
Note that all the special character can be placed in between  except -(Hyphen) and the brackets themselves. You have to provide escape sequence character \ before [, ] and -.
You can change it to below regex to include special character along with square brackets:
The below regex tester can be used to test your regular expression.
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