Putin made the mistake of hiring his mercenaries that were able to perform effectively in the war in Ukraine while at the same time his military was incompetent.
Hiring mercenaries to work in Africa is not super dangerous.
Hiring them in a large military force, a few hundred miles from your capital city, is problematic.
Putin/Russia has allowed private armies (PMCs) to become far too large and powerful. Wagner is by far the best known, but there are many others. These private armies are used around the world as a proxy military to advance Putin's geopolitical, military, and economic interests without the sensitivities or blowback of deploying Russian troops. These armies are growing in number, with some of them answering to oligarchs instead of the Kremlin. Thus far, the primary mission of PMC's has been to undermine western/American interests. That could change quickly.