Is there a published study that shows/proves that mRNA vaccines prevent asymptomatic transmission of SARS-CoV2?

There is no study that shows that. Nor is there a study that shows that "asymptomatic covid" is even a real thing.

There is no study that proves asymptomatic transmission of Sars-Cov2 regardless of vaccine. It's all a lie.

So when my government says 'Stop the spread, get the vaccine', they are lieing?

That depends. If they mean stop the spread of humanity, then they are mockingly truthful.

No absolute proof of Covid or SARS-CoV2.

No proof any vaccine works, in fact, in media story after story, ICU's are full of Covid + patients.

CDC has relaxed guidelines on running PCR tests to the point they can not be relied on.

Of course not.