Another channel, Pravda PL, is part of the Pravda group - a large international network of pro-Kremlin news websites and social media pages. France's state agency for tackling disinformation, Viginum, says it is linked to a Russian IT firm based in Russian-occupied Crimea. According to Newsguard - a company that rates news and information websites for reliability - Pravda is spreading content so widely that it is "infecting" AI chatbot responses. Newsguard tested 10 chatbots with a sample of false narratives shared on Pravda. It says they sometimes repeated or cited the disinformation, while at other times questioning it. Pravda and UKR_LEAKS did not respond to BBC requests for comment. Polska Grupa Informacyjna, the channel that shared the video of the US portraits being burned, shares a mixture of content, including some that gives a Ukrainian perspective. It told the BBC it was "an independent news channel" and its "overriding principle is impartiality", strongly rejecting claims that it promoted pro-Kremlin narratives. It said content on the channel may be shared "as an example of controversial material circulating on the web, without any approval or assessment from the editorial staff". Material may be removed or corrected if it turns out to be inauthentic, it added. Mr Szymkiewicz says the spread of pro-Russian disinformation on Telegram is concerning, as it allows content from state-media sources such as RT and Sputnik to remain present in the Polish-language media landscape, often reaching a wide audience. "Such content is frequently false, manipulated, or outright fabricated," he says. He adds that anti-Ukrainian posts "legitimise and entrench the perspectives and narratives of the Russian regime in Polish public discourse".