A change was causing DUTs to fail repair in large volumes. Richard confirmed that the problem is fixed:

this command shows a DUT that failed, and is now working:
dut-status -g chromeos4-row13-rack1-host8

Richard ran this command to repair the affected DUTs:
dut-status -n -p cq | xargs repair_hosts


This was the revert for the bad change: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/923063/