The Meeting Booked removal reason on the People Removed from a Cadence chart will only appear when you have enabled the Automatically remove people from this cadence if a meeting is booked from related cadence step checkbox in your Cadence settings.

Since the People Removed for a Cadence chart only registers automation from the Cadence settings, the chart will look like your data is not appearing if your team uses the When a Meeting is Booked Automation Rule trigger to remove People from Cadences.

We recommend you update the Cadence settings to automatically remove people when meetings are booked. Also, disable any automation rules for Meeting Booked removals and/or edit the rule so it doesn't include the Remove from all Cadences action.