SpringBoot CGLIB error since upgrading to Spring Boot 3.4.3

We upgraded our application from Spring Boot 3.4.2 to 3.4.3 and ever since doing that, tests that use ApplicationContextRunner have become very flaky and produce this error:

Caused by: java.lang.NullPointerException: Cannot read field "generatedClass" because "data" is null
    at org.springframework.cglib.proxy.Enhancer.nextInstance(Enhancer.java:783)
    at org.springframework.cglib.core.AbstractClassGenerator.create(AbstractClassGenerator.java:321)
    at org.springframework.cglib.proxy.Enhancer.createHelper(Enhancer.java:562)
    at org.springframework.cglib.proxy.Enhancer.createClass(Enhancer.java:407)
    at org.springframework.context.annotation.ConfigurationClassEnhancer.createClass(ConfigurationClassEnhancer.java:169)
    at org.springframework.context.annotation.ConfigurationClassEnhancer.enhance(ConfigurationClassEnhancer.java:121)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.enhanceConfigurationClasses(ConfigurationClassPostProcessor.java:539)
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanFactory(ConfigurationClassPostProcessor.java:311)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:363)
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:153)
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:791)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:609)

The test itself is rather simple and is using ApplicationContextRunner something like this:

    var applicationContextRunner = new ApplicationContextRunner()
        .withUserConfiguration(MyConfiguration.class)
        .withBean(SimpleMeterRegistry);

MyConfiguration is as follows:

@Configuration(proxyBeanMethods = false)
@ComponentScan(excludeFilters = @Filter(type = REGEX, pattern = ".*example\\.core\\.autoconfigure.*"))
@ConfigurationPropertiesScan
public class MyConfiguration {
}

It's to be noted that if the test is run on its own it never fails.