MyISAM reorganize partition corrupt older table format

ID_SUB_SITE int(10) NOT NULL AUTO_INCREMENT,

DATE_METER timestamp / mariadb-5.3 / NOT NULL DEFAULT current_timestamp(),

MEASURE_VALUE mediumint(8) unsigned DEFAULT NULL

PRIMARY KEY (ID_SUB_SITE,DATE_METER,DELAY_IN_MINUTES) USING BTREE,

  KEY EDA_SITE_RESULT_FKIndex1 (DATE_METER),

 KEY EDA_SITE_RESULT_FKIndex2 (DELAY_IN_MINUTES)

) ENGINE=MyISAM AUTO_INCREMENT=873679 DEFAULT CHARSET=utf8mb3

 PARTITION BY RANGE (unix_timestamp(DATE_METER))

(PARTITION p20220220 VALUES LESS THAN (1645398000) ENGINE = MyISAM,

 PARTITION p20220504 VALUES LESS THAN (1651701600) ENGINE = MyISAM,

 PARTITION p20220505` VALUES LESS THAN (1651788000) ENGINE = MyISAM,

...

PARTITION `pDEFAULT` VALUES LESS THAN MAXVALUE ENGINE = MyISAM)

ALTER TABLE DATA_V3.EDA_SITE_RESULT_REAL_TIME REORGANIZE PARTITION  pDEFAULT  INTO ( PARTITION p20220515 VALUES LESS THAN  ( UNIX_TIMESTAMP( '2022-05-16')),  PARTITION pDEFAULT VALUES LESS THAN MAXVALUE)