Before you read a line
Get three things: what the change is meant to do, what it replaces, and the automated report. Without the first two you will review the code against your own assumption of its purpose, which is the most common review failure.
Run the checks first, or read the report if somebody already did. Secrets, unsafe execution, empty catch blocks and syntax problems are settled questions, and spending your attention on them is a waste of the only expensive resource in the process.
Then decide how much attention this deserves: a routine landing page change and a session handler do not deserve the same hour.