See https://github.com/hibernate/hibernate-orm/blob/6746c30275b6600622d82613dc70b1fbf97a2fdf/hibernate-core/src/main/java/org/hibernate/boot/beanvalidation/BeanValidationIntegrator.java#L39-L40C57

public static final String BV_CHECK_CLASS = "jakarta.validation.ConstraintViolation";
public static final String JAKARTA_BV_CHECK_CLASS = "jakarta.validation.ConstraintViolation";

This doesn’t look right, since BV_CHECK_CLASS seems to be a fallback, see: https://github.com/hibernate/hibernate-orm/blob/6746c30275b6600622d82613dc70b1fbf97a2fdf/hibernate-core/src/main/java/org/hibernate/boot/beanvalidation/BeanValidationIntegrator.java#L164-L175

The [JAKARTA_]MODE_PROPERTY two lines below the referenced code above gets it right.

I am pretty sure this was introduced in https://github.com/hibernate/hibernate-orm/pull/4243 by doing some “stupid” find/replace task.