> the image they tweeted alongside was that of broken computers, not of broken DMA cards.

Actually, the image they tweeted shows a ton of PCIe cards.

> DMA cards are not $6k

The ones shown in the image they tweeted are! ($5,800 USD -> https://www.heinodma.com/)

> reports are soft-bricking (i.e., requiring a complete wipe and reinstallation of the OS, not hard-bricking)

I still don't think anything is actually bricked. They are just enabling and enforcing IOMMU, HVCI, etc. which prevents them from using their DMA card to cheat. I'm sure they could restore functionality by removing Riot's games and anticheat, disabling IOMMU and HVCI, etc.