"Achievement prices are lower this round." Message

[actuality]

Hi,
I've gotten an exclamation point icon flashing next to the achievement deck that, when you click on it, pops up a message saying "Achievement prices are lower this round." I have cards in my hand that can lower the cost of achievements (Write about your work and the Solitude muse, each giving a discount of 2 when linked), but the exclamation point is there flashing even if I don't play the cards.

I can't find anything in the rules about achievement price discounts, but I feel I MUST me missing something.

Any insights on this?

[FFMikel]

If you play with 3 or more players, there are grey habits in the market. One of them can reduce or increase the price of achievents for all players. You see the exclamation mark only if a card effect is for all players relevant.