Another possibility is that it's intentionally borderline "oops or maybe not oops" to have plausible deniability while knowing Poland is going to take it extrem

Another possibility is that it's intentionally borderline "oops or maybe not oops" to have plausible deniability while knowing Poland is going to take it extremely seriously. This lets them test Poland's and NATO's reaction to see how much they will tolerate and how eager NATO actually is to mobilize its military.