occur-excluded-properties

occur-excluded-properties is a variable defined in `replace.el'.
Its value is

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Documentation:
Text properties to discard when copying lines to the *Occur* buffer.
The value should be a list of text properties to discard or t,
which means to discard all text properties.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.