Voice control disabled during calls ("to use voice control during calls, enable Siri")

Voice control (accessibility feature to use iPhone hands-free) becomes disabled during calls, which means I'm not able to hang up calls or put them on speaker with my voice. This is important to me because I have very limited use of my hands due to a neuromuscular disability.

I previously was able to use voice control during calls on my previous iPhone (11 Pro) and I believe I had the latest iOS, but after upgrading my device this no longer works properly.

I do sometimes get a notification that says "to use voice control during calls, enable Siri" which doesn't seem to make sense because Siri is enabled, and I have looked through the settings numerous times to find one that is disabled with no luck.

Would be great to know if others are having the same issue, and hopefully have this fixed in a future update.