The issue you’re experiencing with GA4 could be attributed to a variety of factors. It’s possible that something is amiss with how your website is handling its referrer. Alternatively, there could be other issues at play. You’ve tried to manually create parameters to pass down source or medium information by using Java to extract value from cookies. This approach seemed promising initially, but ‘unassigned’ data increasing over time seems to suggest an issue persists. Furthermore, as you’ve observed, the referrer value appears accurate with your other GA accounts, leading to even more confusion as to why the same isn’t true for this particular site. Unfortunately, without more information, it is challenging to provide a definitive solution to your problem.