It just automates the manual workaround: It tells your system to use another mic, not the bluetooth one, so that the bluetooth headphones go back to listen-only mode and doesn't have to operate in its inferior full-duplex mode. So you'd use the headphones only for hearing, and your computer's internal mic (or another external mic, like a webcam's or a standalone USB one) does the recording input.
I do that for all my calls and games already, but I just have to manually set it in the OS (and sometimes on a per-app basis). It only takes a second and usually remembers.
If the app were a one-time purchase I'd probably buy it just to avoid the hassle, but definitely not paying a subscription for something that's so easy to do on my own. As a compromise, I'd also be OK with a OS-version tied upgrade pricing, like you pay $x for the macOS 15 version, but when the next breaking OS update comes that requires an update, you can pay $y after the upgrade discount to get the newest version that works with the new OS.
The default behaviour is designed intentionally to 'degrade to the least-costly codec license' .. since the codecs available to the end user are one of the only ways that different headset/headphone manufacturers can differentiate, doing whats necessary to degrade to the least common denominator allows developers to route around the issues imposed on them by management: namely, don't promote the features of other headset manufacturers, needlessly.
