We've mostly looked at "Total reviews" and "Total comments". When I put the action in place, I told the team that the goal was for everyone to contribute to the process.
I was expecting to look at the stats, make some observations and action items and bring it up during our 1:1. I didn't even need to do that. Everybody took it to heart and contributed in different ways. Our most junior engineer ended up contributing in the most meaningful way and set a new standard for how far we take testing.
At this point, it's pretty clear that I see this more as a tool for individuals. For me, I am a bit constrained on time, I can check the table, notice a variation in the number (the action doesn't show variation so I do it out of memory) and decide to take an hour to explore the contributions. The goal being: how can I help them grow?
As an IC, I perhaps could project myself a bit based on my experience, if I am a junior engineer then I can see who comments the most, explore their comments and learn from them. As a tech lead, I'd want to make sure the tone of the comments are constructive (ie. definitely not toxic).