[Solved] STT engine used in api.mycroft.ai

Enyone knows which STT engine is used when POST /v1/stt?lang=en-US…?

I think eventually is gonna be OpenSTT, but I don’t know which one is currently used.
Does it have some learning maching, can it learn new words/phrases,
what are the main features?

the engine is google STT

Thank you for the response Jarbas!