Why isn't activity name one of the Terra activity enums?

metadata.name carries the user's custom activity title from the provider and can be any free-text string.

metadata.name carries the user's custom activity title from the provider and can be any free-text string. It is not restricted to enum values.

The standardised Terra activity classification lives in the type field, which uses the activity enum.

A free-text name alongside a valid type value is expected behaviour.