ALTER TABLE...ADD KEY creates corrupted index on virtual column

--source include/have_innodb.inc

CREATE TABLE t1(a INT PRIMARY KEY, b INT, g INT GENERATED ALWAYS AS(b)VIRTUAL)

ENGINE=InnoDB;

INSERT INTO t1 VALUES (1,1,default);

ALTER TABLE t1 ADD COLUMN c INT;

ALTER TABLE t1 ADD KEY(g);

CHECK TABLE t1;

SELECT g FROM t1 FORCE INDEX (g);

DROP TABLE t1;

==469741== Uninitialised byte(s) found during client check request

==469741==    at 0xD23BEE: dfield_dup (data0data.ic:172)

==469741==    by 0xD23BEE: row_merge_buf_add(row_merge_buf_t*, dict_index_t*, dict_table_t const*, dict_table_t const*, fts_psort_t*, dtuple_t*, row_ext_t const*, unsigned long*, mem_block_info_t*, dberr_t*, mem_block_info_t**, TABLE*, trx_t*) (row0merge.cc:841)

==469741==    by 0xD26DC2: row_merge_read_clustered_index(trx_t*, TABLE*, dict_table_t const*, dict_table_t*, bool, dict_index_t**, dict_index_t*, fts_psort_t*, merge_file_t*, unsigned long const*, unsigned long, dtuple_t const*, dict_add_v_col_t const*, unsigned long const*, unsigned long, ib_sequence_t&, unsigned char*, bool, pfs_os_file_t*, ut_stage_alter_t*, double, unsigned char*, TABLE*, bool) (row0merge.cc:2358)

Uninitialized bytes in __msan_check_mem_is_initialized at offset 0 inside [0x7290000b90f0, 4)

==457772==WARNING: MemorySanitizer: use-of-uninitialized-value

    #0 0x55a19150c8f0 in dfield_dup(dfield_t*, mem_block_info_t*) /mariadb/10.5m/storage/innobase/include/data0data.ic:169:3

    #1 0x55a19150c8f0 in row_merge_buf_add(row_merge_buf_t*, dict_index_t*, dict_table_t const*, dict_table_t const*, fts_psort_t*, dtuple_t*, row_ext_t const*, unsigned long*, mem_block_info_t*, dberr_t*, mem_block_info_t**, TABLE*, trx_t*) /mariadb/10.5m/storage/innobase/row/row0merge.cc:835:3