Not that I don't believe its possible to fix a lot of bugs, I also wonder what the actual dynamic was. Were the people in team working much more than usual as well? Given its Google, I wouldn't be surprised if there was an "internal push" to fix more bugs over next X sprints so that they can publish this blog and some manager can show impact and AI adaption to his superior.
2. Code reviews and security reviews happen quicker and produce more findings.
I would think that (m)any team(s) using AI might also be seeing a higher rate of finding and fixing issues.
Even the Linux Kernel (I'd say Windows and Apple too) are seeing the same phenomenon.