Nested Split Materialized causes Performance Loss with Version 11

Hello,

Attached you will find a database dump that contains a part of my database.

With MariaDB version 11, I am experiencing a significant performance loss with a specific query.

With version 10.11, the following query takes only 0.036 seconds:

SELECT 

    S.*, B.*

FROM Teilnehmer_1 S

INNER JOIN Buchholzpunkte B ON B.TerID = S.TerID AND B.TnNr = S.TnNr;

134 rows in set (0.036 sec)

With version 11.4.2, the same query takes over 11 seconds.

134 rows in set (11.431 sec)

I tested this in a virtual machine using Docker with the images: mariadb:11.4.2 and mariadb:10.11.

If you need any further information, please let me know.

Best regards,
F.K