The following option in the Doxyfile can be used to hide the trailing "Class Reference" text from a page title.

# If the HIDE_COMPOUND_REFERENCE tag is set to NO (default) then Doxygen will
# append additional text to a page's title, such as Class Reference. If set to
# YES the compound reference will be hidden.
# The default value is: NO.

HIDE_COMPOUND_REFERENCE = YES

But this does not work for Namespace pages, which still have the "Namespace Reference" text appended. This is an issue particularly for those using the OPTIMIZE_OUTPUT_JAVA tag, since that presents namespaces as packages. The result is documentation where clicking on Packages takes you to a page that says Namespace Reference, which is a little misleading.

# Set the OPTIMIZE_OUTPUT_JAVA tag to YES if your project consists of Java or
# Python sources only. Doxygen will then generate output that is more tailored
# for that language. For instance, namespaces will be presented as packages,
# qualified scopes will look different, etc.
# The default value is: NO.

OPTIMIZE_OUTPUT_JAVA   = YES

Running Doxygen 1.13.2 on Windows 11.

Example

Two sourcecode files.

demo_class.py

class demo_class():
    """
    This is a demo class
    """

demo_module.py

"""
In Python nomenclature, this file is a module.
"""

def demo_function_1():
    """
    This is a demo function
    """
    
def demo_function_2():
    """
    This is another demo function
    """

And the following modifications to the Doxyfile.

OPTIMIZE_OUTPUT_JAVA   = YES
HIDE_COMPOUND_REFERENCE= YES

The resulting documentation has a Packages section and a Classes section.

However, the page for the demo_module says Namespace in the title, even though it is in the Packages section.

Whereas, the page for the demo_class has Class hidden from the title by the HIDE_COMPOUND_REFERENCE setting.