InnoDB: index records in a wrong order upon CHECK with DESC index

--source include/have_innodb.inc

CREATE TABLE t (pk INT PRIMARY KEY, a VARCHAR(1), KEY (a DESC)) ENGINE=InnoDB;

INSERT INTO t VALUES (1,NULL),(2,'x');

CHECK TABLE t EXTENDED;

DROP TABLE t;

CHECK TABLE t EXTENDED;

Table	Op	Msg_type	Msg_text

test.t	check	Warning	InnoDB: The B-tree of index a is corrupted.

test.t	check	error	Corrupt

DROP TABLE t;

bug.flag1a                               [ fail ]  Found warnings/errors in server log file!

        Test ended at 2025-01-14 22:10:02

line

2025-01-14 22:10:01 4 [ERROR] InnoDB: index records in a wrong order in `a` of table `test`.`t`: TUPLE (info_bits=0, 2 fields): {NULL,[4]    (0x80000001)}, COMPACT RECORD(info_bits=0, 2 fields): {[1]x(0x78),[4]    (0x80000002)}

2025-01-14 22:10:01 4 [ERROR] InnoDB: Flagged corruption of `a` in table `test`.`t` in CHECK TABLE-check index

commit 3761a7fec8a273c06d52f89bccf11e50cbe5a89d (HEAD, origin/main, origin/HEAD, main)

Author: Marko Mäkelä

Date:   Fri Jan 10 16:40:55 2025 +0200

    MDEV-35312 page_cur_search_with_match() could avoid rec_get_offsets()