https://www.planetf1.com/news/lewis-hamilton-f1-2026-ruling
So FIA set to annouce a ban on wind tunnel / CFD design work for 2026 cars until january 2025. To stop some teams i.e. RedBull gaining an advantage going into 2026. They didnt say RB, but its obvious who they mean.
Also a few team bosses have said due to the cost cap they wont be developing their 2025 cars which will be a tweak on the 2024 cars. So it looks like if you dont nail your car performance by the summer break of 2024 your stuck with that underperforming car for all of 2025.