Mumble is like a reliable Toyota Corolla. You will turn no heads, but it has all the features you would need for the task (encryption, room hierachies, ACL, machine-learning-enhanced noise canceling, positional audio, choice of method input like push-to-talk, mini UI overlay atop games), and does them efficiently.
…And like a Toyota Corolla, there’s probably a decent upgrade out there, but you might be compromising on more than you think. Want a car without the manufacturer tracking you or bloated, touch-screen navigation? Many ‘modern’ VoIP options, especially proprietary ones, are literally doing the latter.