Become the in place (?)

What is the meaning of the second sentence:

There is a jazz band on Friday which is always crowded.
It is becoming the in place to go.

How is “the” coming before “in”? Is that an idiom?

The word “in” can be used as an adjective!
And here it is, and it means “fashionable/in vogue/popular”.

Another example:
It’s the in thing to do. (meaning it’s the cool thing to do)

‘in place’ is idiomatic. It means the fashionable place.
It is becoming the most fashionable place/ the place where people want to be seen.

The first sentence is poorly phrased. Friday is not crowded. The place is.
There is a jazz band on Fridays and the place/it is always crowded.

Very interesting.
Thank you very much for insightful comment and revision.