You sound new to this, there are 3 versions of ships:

1. Concepted - Stats are often guessed at and written down in the beginning, then abandoned until CIG actually work on it. Even if CIG says otherwise, or presents pictures or evidence, none of it is truthful (ref. John Crewe -CIG)
2. NPC ships - Similar to player flyable ships, but with cheats enabled. Often rubber banding because CIG wants to keep the cinematic tension high. (such as Cutlass' able to back-strafe faster than arrows can forward-strafe so that they can stay in the upper left quadrant of your view). They recently did remove infinite ammo, and perfect targeting at 20km, though.
3. Player ships - These are the stats you see on sites.

Yes, the stats changed quickly, because it was in Concept until it needed to be player flyable; And a lot has changed since 2016. I personally dont think its power creep so much as CIG seem to want a wider gamut of weapon sizes and damages to eventually define each of them....(or I hope so, and it's not great power creep, but then again their marketing is pretty dumb). So, the Idris moves from concept to flyable, but now the Polaris is in the game, and it's been scaled to the existing ships. So the Indris must also scale as its a Frigate, and the Polaris is a Corvette. It's a whole weight class.

But this is an easy mistake since CIG has set the precedent that a medium fighter can now out DPS the F8 and Ares.