For non-prepared updates, this is not an issue as commit timestamp is the same as the durable timestamp.

However, this comparison is wrong if two updates are both prepared updates which have different commit and durable timestamps.

For example, if the current update's commit and durable timestamps are 100 and 120, and the previous update's commit and durable timestamps are 80 and 110. This is a valid usage but since the check is comparing 100 against 110 instead of 100 against 80, it will wrongly fire.