Static SQL conditional WHERE clause from a Function

say i have the following function:

function xx_func 
return varchar2
is

    l_value varchar2(1);

begin

    select  'Y'
    into    l_value
    from    func_table
    where   lookup = 'hello';
    
    RETURN l_value;
    
EXCEPTION
    WHEN NO_DATA_FOUND THEN
        l_value := 'N';
        RETURN l_value;
end xx_func;

Now, in the current PL/SQL code, we have this:

DECLARE

    l_optin varchar2(100);
    t_col1  varchar2(100);

BEGIN

    l_optin := xx_func;
    
    if l_optin = 'Y' then
    
        select  col1
        into    t_col1
        from    xx_table_1 xx1
            ,   xx_table_2 xx2
        where   1=1
        and     xx1.t_col2 = xx2.t_col2;
        
    else

        select  col1
        into    t_col1
        from    xx_table_1 xx1
            ,   xx_table_2 xx2
        where   1=1
        and     xx1.t_col2 = xx2.t_col2
        and     xx1.t_col3 = xx2.t_col3;
        
    end if;
    
END;

I wanted to code it like this to make it shorter:

DECLARE

    l_optin varchar2(100);
    t_col1  varchar2(100);

BEGIN

    l_optin := xx_func;
    
    select  col1
    into    t_col1
    from    xx_table_1 xx1
        ,   xx_table_2 xx2
    where   1=1
    and     xx1.t_col2 = xx2.t_col2 
    and     ((xx1.t_col3 = xx2.t_col3 and l_optin = 'N')
    OR       (l_optin = 'Y'));
            
END;    

The code above tells me If l_optin is 'N' then evaluate xx1.t_col3 = xx2.t_col3. if l_optin = 'Y', then don't evaluate xx1.t_col3 = xx2.t_col3. I tried testing it locally and it works but my co-worker says it won't work on all scenarios. The columns are not nullable.

Are there any possible scenarios that this wouldn't handle?

Note:

• We cannot use Dynamic SQL
• this sample code occurs multiple times in the package of over 14000 lines, hence, it's quite hard to read at that point.