I wasn't aware of that. But I did know that -
PMCs are technically illegal under Article 359 of the 1996 Russian Criminal Code, which states: “Recruitment, training, financing, or any other material provision of a mercenary, and also the use of him in an armed conflict or hostilities, shall be punishable by deprivation of liberty for a term of four to eight years.”
https://www.csis.org/analysis/putins-proxies-examining-russias-use-private-military-companies

"the use of him in an armed conflict" - that implicates Prigozhin and probably Putin (just need some evidence for the link which is obviously there).