Yes this is true about the Schengen zone at the beginning of this year. From multiple articles out, it appears that the official date that airports will end passport checks is on 26 March 2023. As I quote from one article, "The airports of Croatia are set to end their checks for all travellers of the European Union/Schengen Area on March 26, 2023, and in order to avoid any possible problems, they have already started to make changes..." "To ensure that everything goes smoothly once the checks at the airports end, the largest and the busiest airport in Croatia, Zagreb Airport, has already announced that it is making more space for the waiting areas. Moreover, the Zagreb Airport has decided to move the departure passport control counters from its terminal on the third floor to the terminal on the second floor."
So it appears that ZAG has already started to make changes and should expect everything to be finalized by 26 March 2023. How exactly this will change the official layout of the ZAG airport terminal, that is the uncertainty. I am not sure when your trip is, but any updates from your experience would be interesting to hear during these new times!