Could you check what is preventing this MySQL query to correctly running?

Hi Experts

Could you check what is preventing this MySQL query to correctly running?

SELECT
                id_reclamacao,
                sise,             
		fk_seguradora,
                nome_reclamante,
                data,
                case TIMESTAMPDIFF(HOUR, data, IFNULL(data_atendimento, CURRENT_TIMESTAMP))
                 WHEN <24 THEN 'V'
                 WHEN >=24 AND < 36 THEN 'A'
                 WHEN >=36 AND < 48 THEN 'L'
                 ELSE 'Ve' 
                 END AS sla,
                nome_agente,
                procedencia
FROM system_reclamacao

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The error produced:

Thanks in advance