CREATE TABLE t1 (pk INT PRIMARY KEY, a YEAR UNSIGNED) ENGINE=InnoDB
ROW_FORMAT=REDUNDANT;
INSERT INTO t1 VALUES (1,2021),(2,21),(3,0);
UPDATE t1 SET a = NULL;
# shutdown server
# remove datadir
# xtrabackup move back
# restart
SELECT * FROM t1;
pk	a
1	NULL
2	NULL
3	NULL
DROP TABLE t1;