Wow, that is quite a difference between those two numbers, huh? Doesn’t really seem right, even with GA4’s tendency to count more users. And you checked for any double GA4 codes so it’s not that. Hmm…
Let’s see, here’s a few things we can do to figure out what’s going on:
1. Take a look at your UA property. Make sure no weird filters are messing with the numbers.
2. Are you comparing the exact same periods for both? Worth double checking.
3. Check all the hostnames you’ve tracked during that time. Maybe GA4 is counting some that UA isn’t?
4. GA4 counts mobile app traffic which UA doesn’t, might that explain the difference?
5. Try checking per section of the site. Maybe GA4 is tracking some places UA isn’t?
After trying all of that, if we got no answers, we might be a bit stuck. It’s not like it’s easy to overcount users, it doesn’t really happen unless you’re trying to make it happen.
Our last resort might be to use the Adswerve’s datalayer debugger extension. This bad boy should allow you to see what’s firing on your pages. Keep in mind that GA4 events are batched, so you need to dive inside the event and double check it’s not counting twice with a different client id. It’s a bit of a long shot, but with numbers this skewed, who knows?