This is only on runs with SE 25:
Test name: jsonb-tck Number of Tests Passed = 294 Number of Tests Failed = 1 Number of Tests with Errors = 0
[INFO] Running ee.jakarta.tck.json.bind.customizedmapping.numberformat.NumberFormatCustomizationTest [ERROR] Tests run: 7, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.554 s <<< FAILURE! -- in ee.jakarta.tck.json.bind.customizedmapping.numberformat.NumberFormatCustomizationTest [ERROR] ee.jakarta.tck.json.bind.customizedmapping.numberformat.NumberFormatCustomizationTest.testNumberFormatField -- Time elapsed: 0.023 s <<< FAILURE! java.lang.AssertionError: Failed to correctly customize number format during marshalling using JsonbNumberFormat annotation on field. Expected: a string matching the pattern '\{\s*"instance"\s*:\s*"123\u00a0456,789"\s*\}' but: was "{\"instance\":\"123 456,789\"}" at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20) at ee.jakarta.tck.json.bind.customizedmapping.numberformat.NumberFormatCustomizationTest.testNumberFormatField(NumberFormatCustomizationTest.java:112) at java.base/java.lang.reflect.Method.invoke(Method.java:565) at java.base/java.util.ArrayList.forEach(ArrayList.java:1604) at java.base/java.util.ArrayList.forEach(ArrayList.java:1604)
It's possible this is a test flaw as the TCK predates SE 25. If so perhaps convert this to a top-level issue and tweak the title.