This a preliminary report, not a completed study. The Data was gathered just 4 weeks after the last participants were enrolled, and just 11 weeks after the first participant was enrolled. Many will have been born (and probably a few more miscarriages) in the 3 months since March 30, but many of the women are still pregnant. The last babies in the study won't be born until November 2021.
The only way they can get to (almost) 82% miscarriage is if 100% of the remaining pregnancies are miscarriages and still births. Based on the data so far, that's not going to happen. But it will be crucial to get the rest of the statistics to know the full story.