The solution to this is actually quite simple! You can wrap your client ID in what’s known as a ‘zero width space’ character before you send it over to GA4. This special character (which is ‘& #8203;’ without the spaces) effectively convinces GA4 to treat the enclosed value as a string, even if it looks like a floating-point number. After you’ve wrapped up your client ID like this, it should show up in BigQuery as a string just as planned!