I think Microsoft is smarter than that, look at Github for example, people have largely forgotten it's owned by MSFT. They would have left Discord as a gaming platform and used it's tech in Teams instead. Teams is so behind Discord in all areas except video quality.
Very poorly polished stuff, to be honest. Before, they always seemed to take great care in making their core product (and the API for it) great. The only thing I can think of that was similarly unpolished was GitHub Enterprise.
I don't think GitHub staff has forgotten. Actions are straight up Azure Pipelines. The code is a huge mess. If I didn't know better I'd say it's obscured by design. Check out the actions/runner repo if you don't believe me. They polished them very well for the hosted version, but the cracks show if you try to use the self-hosted version.
I can't believe anyone at GitHub is particularly thrilled about having a Microsoft technology that broken imposed on them.
Can I just say, while I believe Discord will die anyway if it IPOs (as with anything that believes in infinite scaling), I would have loved to see Microsoft enact the special fucked up kind of integration that only they can manage