The way Russia operates, this could be response to the "Vulkan files" and Gleb Karakulo's defection. Russia likes to get in the last word after they get it worse off on the battlefield or in the news.
I don’t know the answer, but here are some more bits of news.
Russia likely behind U.S. military document leak, U.S. officials say
https://www.reuters.com/world/us/russia-likely-behind-us-military-document-leak-us-officials-say-2023-04-07/
Leaked Ukraine Counteroffensive Plans May Have Been Putin Ploy, Says Expert
https://www.newsweek.com/ukraine-leaked-war-documents-counteroffensive-pentagon-1793177
Ukraine says leaked classified US intel docs which revealed combat death ratio are Russian ploy
https://inews.co.uk/news/world/ukraine-russia-pentagon-secret-documents-classified-counteroffensive-2262409
Ukraine says data leak Russian effort to sow doubt about counter-offensive
https://www.newarab.com/news/ukraine-says-data-leak-russian-effort-sow-doubt-about-counter-offensive
Leaked US plan to build up Ukraine’s forces for counter-offensive ‘is photoshopped’
https://www.telegraph.co.uk/world-news/2023/04/07/ukraines-forces-for-counter-offensive-is-photoshopped-us/
Pentagon’s Ukraine War Plans Leaked on Minecraft Discord Before Telegram and Twitter
https://www.vice.com/en/article/pkadnb/pentagons-ukraine-war-plans-leaked-on-minecraft-discord-before-telegram-and-twitter
More like opinions and speculation, really, but there might be some info. I’ll try to read some of those later.