What punishment will Buddhist laymen get for breaking the precepts?

Discipline: It is a method of forcing self-discipline.

If you break the precepts, you repent. The purpose of repentance is not to repeat it in the future.

As for punishment, I can't say what punishment it is.

It's often said very well

Everything you do has a cause and effect. What you have done and paid can't be called punishment, but it's just returned to you.

In other words, whether you are a Buddhist disciple or not, it is all the same, and there is cause and effect when you do it.

But through your practice, cause and effect can also be changed.