Consider code like:
---
public class NullPatterns {

    public static void main(String[] args) {
        switch (new R(null)) {
            case R(Object o) when o == null -> {} //correct
            case R(Object o) -> throw new AssertionError("Incorrect case!");
        };
    }

    record R(Object o) {}

}
---

Running this leads to incorrect outcome:
---
$ java --enable-preview --source 21 NullPatterns.java
Note: NullPatterns.java uses preview features of Java SE 21.
Note: Recompile with -Xlint:preview for details.
Exception in thread "main" java.lang.AssertionError: Incorrect case!
        at NullPatterns.main(NullPatterns.java:6)
--