From https://docs.oracle.com/en/database/oracle/oracle-database/23/lnpls/plsql-language-fundamentals.html:

A quoted user-defined identifier is case-sensitive, with one exception: If a quoted user-defined identifier, without its enclosing double quotation marks, is a valid ordinary user-defined identifier, then the double quotation marks are optional in references to the identifier, and if you omit them, then the identifier is case-insensitive.

Example 3-1 Valid Case-Insensitive Reference to Quoted User-Defined Identifier

In this example, the quoted user-defined identifier "HELLO", without its enclosing double quotation marks, is a valid ordinary user-defined identifier. Therefore, the reference Hello is valid.

DECLARE
  "HELLO" varchar2(10) := 'hello';
BEGIN
  DBMS_Output.Put_Line(Hello);
END;
/

However, the SymbolVisitor currently fails to recognize this reference correctly, displaying "<no usages>" in the ZPA Toolkit.