At the time of writing it has been flaky or failed completely 22 times in the last 28 days. All of the failures are in 2.5.x so I suspect that https://github.com/spring-projects/spring-boot/issues/24898 may have destabilised things. The failures appear to be due to a timeout popping:
com.datastax.oss.driver.api.core.DriverTimeoutException: Query timed out after PT2S
We should try increasing the query timeout to more than 2 seconds and see if it helps.