WF-1000XM3 batteries adn Sony customer care

I contacted Sony support to inquire about the batteries used in the Sony WF-1000XM3 headphones and asked:

Are the internal batteries Varta CP1254 A3, or have they been upgraded to Varta CP1254 A4/A4X in more recent models?

Their response was:

In reference to your inquiry, we can inform you that this information is not disclosed.

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