The Combat Mission allows Missouri to be the strongest Credit Farming ship in the game per folks that have looked into it. Once the Combat Mission was moved to +30% Credits, there was no further concern on that front.
97k Damage? Can you mention what ships you dealt damage to?
Credit Earnings are altered depending on the Tier of ship you attack. Also, credits are calculated based on %health done, not raw damage, so 97k to a Battleship would be roughly one player's worth of "Health", whereas 20k damage to 5 Destroyers would be something akin to 4.5 players. In short, target selection can be a huge factor in Credit and XP earnings.
If you'd like to learn more about our Economy, there's a great video which details it.
Direct Video Link: https://www.youtube.com/watch?v=0_bXHAqLkKc
I am directly telling you that it hasn't been nerfed. This isn't to say there couldn't be a bug introduced with the new patch, however.
In the post above, I gave possible causes for your issue. If you can provide additional information, I'm sure we can better illuminate why your results aren't matching up with your expectations.
LWM's Testing finalized when the Missouri Combat Mission was increased to +30%
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