> The Polish railways network consists of around 18,510 kilometres (11,500 mi) of track as of 2019, of which 11,998 km (7,455 mi) is electrified. [1]

As only ~65% of the polish rail network are electrified, I'm sure there are still plenty of Diesel powered trains operating in Poland.

[1]: https://en.wikipedia.org/wiki/Rail_transport_in_Poland