During a call, the microphones will pick up the ambient sound regardless of the Ambient Sound Control function setting. This is an effect of the Sidetone function, which allows your voice to be heard naturally and makes it more comfortable to talk during a call. As a result, the noise canceling function works differently on a call than it does when playing music.
If you hear ambient sound, headphones operation sound, or white noise (a small electrical noise with continuous static sound) during a call, that is also an effect of the Sidetone function, not a malfunction.
Hint: For WF-1000XM5 only: The Sidetone function can be turned off. To turn off the function, in the Sony | Headphones Connect app select the System tab and set the Capture Voice During a Phone Call setting to Off.