Wrong result in loose index scan

Noticed this while working on MDEV-32732. With

CREATE TABLE t1 (a int, b int, KEY (a, b));

insert into t1 values (1, 3), (1, 1);

SELECT MAX(b) FROM t1 WHERE (b > 2 AND b < 4) OR (b = 5) GROUP BY a;

drop table t1;

At the current main c92add291e636c797e6d6ddca605905541b2a441 the SELECT statement outputs empty but it should be 3.

It outputs the correct result at the current 10.5 5ebff6e15a0c2e1b8a8e41943540332c757a6d03.

In fact, the bug reproduces at the current 11.4 ef966af801afc2a07222b5df65dddd52c77431dd, but not at (an ancestor) 10.11.11 e69f8cae1a15e15b9e4f5e0f8497e1f17bdc81a4