Here's the direct link to the PDF for the report: https://river.com/learn/files/river-bitcoin-mining-zettahash-report.pdf

Here's the Tweet by the author of the report that kicked off the Twitter thread where this report was shared:
Energized by the overwhelming feedback on our Lightning report, I continued work on @River's next report. After 1.5 months it is done, and I hope you like it. In the free 35-page report we examine: What could Bitcoin mining look like at one zettahash?
#WhenZettahash ๐Ÿงต(7)๐Ÿ‘‡
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There is now also a video covering this article:
What Could Bitcoin Mining Look Like at One Zettahash? #113773
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