MaxScale 24.02.04 not closing DB Connections properly

Hello guys.
On Monday 16th of december around 22:30, we performed an upgrade on our MaxScale from version 24.02.03 to 24.02.04. MaxScale is used as a balancer for MariaDB databases for a website built on TYPO3, running on the Rocky 9 operating system. Specifically, we upgraded maxscale-24.02.3-1.rhel.9.x86_64 to maxscale-24.02.4-1.rhel.9.x86_64. We didn't notice that something is wrong throught 17th of december. On 18th of december we hit the limit.

Practically immediately after the update, the number of open sessions on the database began to increase. During the day, the open sessions, which averaged around 4–5 sessions per second before the upgrade, grew with the increasing load on the website to as high as 750 sessions which is configured max-connections on database. These sessions remained in an idle/sleep state even over night where the load on page is practicaly 0.

Interestingly after some analysing, the sleep time for some sessions increased, for example, to 200 seconds, and then dropped to 0. As a result, even the session timeout did not terminate these sessions. When I enabled logging of all queries on MariaDB, the sessions that remained in the sleep state did not execute any queries. However, the sleep time for these sessions still decreased.

After downgrading back to maxscale-24.02.3-1.rhel.9.x86_64, the situation returned to normal.