Probably a company was hired to make the poster design, and they made whatever they wanted.
They just used the same old CGI which has been floating on internet for 5+ years.
Would be nice to see a new design though.
The mast on the real ship will look exactly the same as Kolkata/Vizag class.
This is an 'official' CGI by DND:
And the scale model:
...give you an idea of the actual design. Unfortunately, for whatever reason they seem to have abandoned the stealthy, flush superstructure in the mid-section (which on the Shivalik served to enclose the RHIB bay):
...the P-17A appears to have significantly less signature management in that portion because of that.
The fore deck though (bow) is properly 'flush', kinda similar to FREMM in that way.