I am monitoring the difference of daily new registered users to our service between the three our database and the two other tools we use to make sure everything is allright: Google Analytics seems to overestimate the number of newly registered users and Facebook to underestimate. Yet it seems that since February 17th, 2020 there these discrepences incremented. And it incremented even more in February 2021.
I haven't found any technical reason about that in the news. My guess would be that there is a time lag?