They used to, then Musk fired all of them.

https://www.cnn.com/2023/02/14/europe/russian-army-prisoners-conscripts-ukraine-intl/index.html

>The scheme to send convicts to the war appears to have grown fast, with figures obtained by CNN from Russia's penal system showing a 27,000 drop in the prison population between March and November last year, when the scheme was just three months old.

The meat grinder needs meat. You think Russia cares where it comes from?