There are certainly situations where, as a reviewer, 5 minutes of goto-definition on a PR branch, or a well-placed debug breakpoint while running a test, is all

There are certainly situations where, as a reviewer, 5 minutes of goto-definition on a PR branch, or a well-placed debug breakpoint while running a test, is all you need to write a more prescriptive comment than “I don’t understand how this data flows” - and thus avoid both a follow up meeting and the need to pair program in the first place. Pairing absolutely has its place, but it’s not always the most optimal use of time.