For Openshift/k8s environment, it's common for application pods to output log into stdout.
However, by stdout setting, spring-boot-starter-undertow's access log is mixed up with runtime log.[1]
To avoid the issue, EAP undertow subsystem has an option, "use-server-log=true". With the option, undertow access log handler will use the same logging framework used by the EAP runtime and the option will resolve the mixing log issue.[2]
Please consider implementing a same kind of option for CSB too.

[1]
For logging access log, spring-boot-starter-undertow uses DefaultAccessLogReceiver which does not use the same logging framework used by the Spring Boot application.
https://github.com/spring-projects/spring-boot/blob/3.4.x/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/undertow/AccessLogHttpHandlerFactory.java#L61-L69
https://github.com/undertow-io/undertow/blob/2.3.x/core/src/main/java/io/undertow/server/handlers/accesslog/DefaultAccessLogReceiver.java

[2]
https://github.com/wildfly/wildfly/blob/main/undertow/src/main/java/org/wildfly/extension/undertow/AccessLogService.java#L85-L114
https://github.com/undertow-io/undertow/blob/2.3.x/core/src/main/java/io/undertow/server/handlers/accesslog/JBossLoggingAccessLogReceiver.java