Paradox Interactive has announced the Crusader Kings III: Friends & Foes event pack releases September 8 and they also mentioned some price rises.
Firstly, mentioned in a forum post, the price of Flavor Packs (like Northern Lords and Fate of Iberia) will increase from 6.99 USD to 12.99 USD. Paradox said this was to "reflect the overall value of this kind of content moving forward" so expect that price for future similar packs starting September 13. However, the main game and the Royal Court expansion prices remain unchanged.
Also Crusader Kings III: Friends & Foes was announced that arrives on September 8. This is an event pack, not a big expansion, adding in over 100 new events and a bunch of new music to accompany you on your conquests:
Crusader Kings III is simply one of the best games they've made to me, next to Stellaris for having plenty of depth and not being completely overwhelming and confusing like some of their other titles. I must admit my temptation to get a whole bunch more events is something.