Apple support has this page which explains how to define which "modes" the Airpod Pro will switch between with the physical button. Note that this requires an iOS device. Using my iOS device, I can configure them to have all 3 modes available [transparency, off, noise-canc].
If I then take the Airpod Pro and connect them to any other bluetooth source, they will retain that setting. This is good.
If I then take the Airpod Pro and connect to a MacOS device (e.g. my MacBook), they immediately revert to having only 2 modes available [transparency, noise-canc]. I.e. the "off" setting is disabled. This is bad.
After this, AFAIK, the only way to get the 3rd mode back (tied to hardware button control) is to reconnect to an iOS device.
I'm hoping I'm mistaken. Please let me know if there is a way to keep them configured for all 3 modes, all the time, even after connecting to MacOS.