[jech]

> But on the other hand, we also don't know if this is a foreign misinformation campaign or just a politically disgruntled Pole

The videos contain at least one mistake that indicates that they were written by a native speaker of Russian (the use of the word prawilny, which is a Russian word (правильный) and doesn't exist in Polish).

It's circumstantial evidence, granted, but enough to point at a Russian origin, at least in the absence of further information.