Thanks @hobovsky! Actually I wasn't aware of formatting issues in this context leading to such situations - some tweaks and reformatting helped to fix it.

It seems the test case handling (or something else in the environment) is broken. I run successfully a batch of tests which all pass not using codewars-environment. Using the exact same tests with of course the same solution some tests break when executed in codewars. Commenting out some of those and using only a subset seems to work, but in non-deterministic way. Meanwhile I have simplified my solution to very basic Java code verifying in terminal and IntelliJ. In addition I logged the failing numbers while traversing the given array and use those numbers (bills) in my own test cases, where they all just pass if not executed in codewars-environment. Anyone having similar observations?