This morning I got the original Cove voice back on my iPad and iPhone! Here were the steps I took:
Settings>Personalization>Customize ChatGPT>Advanced>Turned off Advanced Voice.
Then back to Settings>Voice.
Went through all the voice choices and re-chose Cove.
When I returned to the chat mode and touched the voice mode squiggle, the ball came up black instead of blue and the voice was the original Cove.
I hope it will stick!
Pinging @Lala.Kent
You probably want to see/hear this