Seems more likely to me that Ukrainian forces are just seeking any way they can to hurt Russian forces. If Russian mercenaries are making money that funds the invasion of Ukraine and making allies for the Russian government by fighting in Africa and the Middle East, it makes sense for Ukraine to attempt to counter that where they can. It’s also pretty reasonable for Azawad fighters to see Ukraine as an ally given that they’re fighting a Russian-backed government employing Russian mercenaries.
Not just money, there’s a risk that if Wagner is successful there, they could start recruiting from there more soldiers to send to Ukraine.