This message presents the narrative of a corrupt and fraudulent mainstream media controlled by political elites and promoting their agenda to society, see examples here and here.
The story of Mateusz Piskorski has been a hot topic for all the mainstream Polish media since 2016 as were quite a few Polish citizens arrested with the accusation of spying for Russia. There are hundreds of articles and TV reports on this person (his arrest, background, charges, legal case). Moreover, two major Polish newspapers quoted parts of his letters sent from prison (here and here) - in these letters Piskorski defended himself from the accusations in espionage. According to words of Piskorski, he is accused of manipulation with public opinion and promotion of messages close to Russian narratives - from his point of view, these actions cannot be perceived as espionage.
In 2016, Mateusz Piskorski was arrested and accused of espionage on behalf of Russia and China, for which he allegedly received financial remuneration between 2009 and 2016. Piskorski was reported in Polish media to have collaborated with fascist organisations in Poland and Russia, "observed" fake elections and referenda in Transnistria and Crimea, organised violent provocations aimed at exacerbating ethnic tensions in Ukraine, and met with Kremlin-backed militants in Ukraine's occupied Donbas region.
In May 2019, Piskorski was released from the arrest pending trial, remaining under police supervision.
Sputnik Polska devotes a lot of space to the case of Mateusz Piskorski. He himself is now a contributor to Sputnik's website.