Is it vulnerable to the application if a CDT has more than recommended number of fields (I have a CDT with 500 fields approx).

I consider this to already be or at least become an issue on many levels. BTW, this feels like flawed requirements ...

What is the use case here?

Did you consider a key-value store?

 sir, I asked to my Friend and he gave me the use case: we have one large pivot interface (which has six different units and contains every day calendar field) where user fill data quarterly and for hold these values we created this more then 500 field CDT.

Note we are saving this data in external system so we use integration for insert and update.

Then, why even bother using a CDT. When you exchange data via JSON, there is no need for a CDT.

Then, why even bother using a CDT. When you exchange data via JSON, there is no need for a CDT.