Reboot. Restart. Re-do. What do I mean?
Sometimes you just have to scrap the old and start anew. I mean, of course, tagging for GA/GA4.
I really dislike this advice, especially if you have lots of history. But recently I’ve encountered situations where, in auditing an implementation, there have been so many instances, versions, revisions to the tagging that it has just never been right or even consistently wrong.
And, in these cases, the best/only path forward it to restart. You can restart with the knowledge that if/when the historic data had been incorrect – consistently incorrect, it could be used directionally. But sadly, sometimes that is not even an option.