This repository demonstrates a change between Spring Boot 3.1.6 and 3.2.0.
With Spring Boot 3.1.6, a Spring WebFlux application with Micrometer Observation would fail to start when multiple beans of type ServerRequestObservationConvention are defined, which seems like expected behavior to me.
However, with Spring Boot 3.2.0 this behavior changed, and now you don't get a startup failure when multiple ServerRequestObservationConvention beans are defined, and silently DefaultServerRequestObservationConvention is used.
I think this is unexpected behavior, which should be restored to what it was in Spring Boot 3.1.6.
The tests in the spring-boot-3.1 and spring-boot-3.2 branches of this project illustrate this issue.
This issue has been reported on GitHub here.