Mute is surprisingly difficult to implement in bluetooth.
Anker is using AVRCP (typically v1.4) to send play/pause/next messages back to host. Mute is not part of AVRCP. Meaning the mute would (probably) have to be done locally to the headphones.
Anker is using “stateless” being host and device in that a “mute” is not inherently stateful at the host, so any hiccup would leave the headphone “not working”.
I think that’s why they haven’t done it yet. But they could if enough asked for it.
Physically how they would implement it is when the headphone mute is touched, the microphone in the headphone would be disabled. Issue then you have two places to mute (phone and headphone) so someone could think they are muted, and weren’t, or not muted and are. Unreliable.
I am not so sure it would be reliable. But they’re more expert at this than any of us here. Keep asking is my advice to press them.
Mute wired is far easier “break the wire”.
As in it can be added to future products but physically impossible to implement on existing products (as far as I can tell, they’re the experts).