Affected Version:

What steps will reproduce the problem?
1. Create a CL and get it LGTMed by one person.
2. Add a new reviewer whose user name sorts alphabetically before the old reviewer's.

What is the expected output?

The green highlight should stay on the original reviewer.

What do you see instead?

The green highlight stays in the first position and thus against the wrong reviewer.

Can see this here:
https://screenshot.googleplex.com/JmrbEr1Nukn.png

Note it doesn't match the +1s below it. Those are correct.

Also reloading the page fixes the problem.