after changing YEAR to YEAR(+ 1 year)-1,value unexpectedly change

mysql> SELECT YEAR(dkw78.c4) AS col_1 FROM t1 AS hdy31 RIGHT JOIN t3 AS dkw78 ON (dkw78.c2 = hdy31.c1);

+-------+

| col_1 |

+-------+

|  2020 |

+-------+

1 row in set (0.00 sec)

mysql> SELECT YEAR(dkw78.c4 + INTERVAL '1' YEAR) - 1 AS col_1 FROM t1 AS hdy31 RIGHT JOIN t3 AS dkw78 ON (dkw78.c2 = hdy31.c1);

+-------+

| col_1 |

+-------+

|  NULL |

+-------+

1 row in set, 1 warning (0.00 sec)

DROP DATABASE IF EXISTS test;

CREATE DATABASE IF NOT EXISTS test;

USE test;

CREATE TABLE t1 (

    c1 INT NOT NULL AUTO_INCREMENT,

    c2 VARCHAR(255) NOT NULL,

    c3 VARCHAR(255) NULL,

    c4 INT NULL,

    c5 DATE NOT NULL,

    c6 VARCHAR(10) NOT NULL,

    PRIMARY KEY (c1)

);

CREATE TABLE t3 (

    c1 INT NOT NULL AUTO_INCREMENT,

    c2 INT NOT NULL,

    c3 INT NOT NULL,

    c4 YEAR NOT NULL,

    c5 TIME NULL,

    c6 TINYINT NULL,

    c7 SMALLINT NULL,

    c8 MEDIUMINT NULL,

    c9 BIGINT NULL,

    c10 LONGTEXT NULL,

    c11 GEOMETRY NULL,

    c12 TINYTEXT NULL,

    c13 TINYBLOB NULL,

    c14 SET('x','y','z') NULL,

    c15 TINYINT(1) NULL,

    PRIMARY KEY (c1)

);

INSERT INTO t1 (c1, c2, c3, c4, c5, c6) VALUES (2579, 'sample_3bKxOOAviOsEZUX601LmXKqAKYyFXmj2e4D7HAznt', 'sample_rsqgYiakfFgdOjtCinonEzRmFDZOw3WgjR6pBcWuVxsaZQBYHIhV7PQILJt2oqOKOS6vxmRm4Z3QzZvLDn2bvxJpLCMOW81RuIvRNJjOdT3U5yh943Tnq0eJffCjCPpgdtPQZcGktYzTx1AQaVwG7nHkZj0REQs9mlkypriOTLujStvDuuKw7geoEh0WrE2FV4DzgkCAar0tDrCh', 34, '2025-02-06', 'sample_m');

INSERT INTO t3 (c1, c2, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13, c14, c15) VALUES (4992, 2579, 9871, 2020, '2023-01-01 22:44:35', 46, 25, 79, 9, 'sample_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', ST_GeomFromText('POINT(89.285446 -33.318821)'), 'sample_YFFtbMWTmNenOjXxHy0YfyUoPQSfJAVvKICpHFIIMenooB36lYoAS3hPjCLJlPqpVho', X'D4A7E898B817C88330CBBBE9B0B6C2A736', 'z', NULL);

SELECT YEAR(dkw78.c4) AS col_1 FROM t1 AS hdy31 RIGHT JOIN t3 AS dkw78 ON (dkw78.c2 = hdy31.c1);

SELECT YEAR(dkw78.c4 + INTERVAL '1' YEAR) - 1 AS col_1 FROM t1 AS hdy31 RIGHT JOIN t3 AS dkw78 ON (dkw78.c2 = hdy31.c1);