Basic math operations with SUM() - unexpected values

we had this problem: updated version of MariaDB Columnstore from 1.2.2 to 1.2.4 and nonsense started.

We have these columns col1, col2 both are DECIMAL(15,3) there was already working query to calculate these two columns (see alias A) and this wasn't calculating right when col2 had zero sum - after db update. Alias B was first approach which didn't help. And C was solution for proper working.

I want to know explanation why this happened and what caused this behaviour.

SELECT
id,
SUM(col1) AS c1,
SUM(col2) AS c2,
SUM(col1 - col2) AS A,
SUM(CAST(col1 AS DOUBLE) - CAST(col2 AS DOUBLE)) AS B,
SUM(CAST(col1 AS DECIMAL(15,3)) - CAST(col2 AS DECIMAL(15,3))) AS C
FROM table GROUP BY id

1.2.2:

+----+----------+--------+-----------+
| id |    c1    |   c2   |     A     |
+----+----------+--------+-----------+
|  1 | 1199.940 |  0.000 |  1199.940 |
|  2 |  979.860 | 69.990 |   909.870 |
+----+----------+--------+-----------+

1.2.4 with extra SUMs

+----+----------+--------+-----------------------+---------+-----------+
| id |    c1    |   c2   |           A           |    B    |     C     |
+----+----------+--------+-----------------------+---------+-----------+
|  1 | 1199.940 |  0.000 | -9223372036853575.868 |       0 |  1199.940 |
|  2 |  979.860 | 69.990 |               909.870 |  909.87 |   909.870 |
+----+----------+--------+-----------------------+---------+-----------+