In the hubspot knowledge base it is stated “A fragment identifier, denoted by the hash mark #, must be located after the last forward slash in your URL.”
But this is false:
A fragment identifier component is indicated by the presence of a
number sign ("#") character and terminated by the end of the URI.
- RFC 3986: Uniform Resource Identifier (URI): Generic Syntax | RFC Editor
Forward slashes are absolutely valid within URL fragment identifiers, and many applications use this.