Voice en_US-bryce-medium.onnx tells "Don" instead of "John"

[gnusupport]

(rcd-tts-and-speak "John")

Gives me clear "Don"

but

(rcd-tts-and-speak "John and John")

gives me clear "John and John".

When there is single word beginning with J it is spoken as D in this voice model en_US-bryce-medium.onnx

So "Joseph" is pronounced as "Doseph", "Jane" becomes "Dane", but if I use "and Jane" it is pronounced correctly.

What is here the problem?