Identify which index's rebuild operation is causing the log file to grow

We have a database, in full recovery model, which goes under index rebuild maintenance once a week. There is an index which is causing the log file to grow. I have log file growth event alerts enabled, it always happens at the same time and continues for a few hours and stops later, so quite sure it is the same index all the time. I'm not sure whether it is a clustered or non-clustered index but suspect a clustered index on a large table, of which there are a couple, is causing this. After the maintenance job completes, I shrink the log and it stays stable for the whole week. How can I identify which index is causing the file to grow? Prefer to avoid logging solutions such as extended events or audit.