Final answer:
The limitation of an AFTER UNDELETE trigger is that it can only be used when records are restored from the recycle bin and cannot react to hard deletes or operate on records if the recycle bin feature isn't supported. It also lacks context on the record's previous state before deletion and restricts certain operations within the trigger execution context.
Step-by-step explanation:
A limitation of an AFTER UNDELETE trigger is that it can only be used with recycle bin objects when a record is restored from the recycle bin. Since it is dependent on the recycle bin feature, it is not possible to use this trigger to react to records being deleted in ways that bypass the recycle bin, such as when records are deleted using a hard delete operation, or if your organization does not support the recycle bin feature.
Another limitation is that AFTER UNDELETE triggers do not provide any context about the state of the record before it was deleted, which may be necessary for some business logic. Moreover, there are limitations on the types of operations that can be performed in an AFTER UNDELETE trigger. For instance, you cannot perform DML operations on the restored record within the same trigger execution context which can restrict what can be done programmatically upon undeletion.