I'm basing this on my own fuzzy memory without looking up the Star Trek lore online, but isn't there a huge global war sometime in the 21st century? And this ultimately leads to the events seen in
First Contact where Zephram Cochrane invents the warp drive and meets the Vulcans, which in turn leads to a golden age of peace for humanity? It would be an interesting -- although thoroughly depressing -- twist if the single event in 2024 that Picard and his crew must change is something that leads to the electoral
defeat of a loathsome Trump-like fascist in that year's US election. Without that person in power, the events that will cause WWIII and ultimately First Contact never happen. It would sort of be like the opposite scenario from
The City on the Edge of Forever where Kirk has to allow Edith to die in order to ensure 20th century fascism is defeated. In this scenario, Picard has to
save a 21st century fascist leader in order to ensure WWIII occurs but humanity ultimately has a brighter future.
Edit: I just looked it up on Memory-Alpha. In the fictional Star Trek future, WWIII starts in 2026, so the timing for this certainly checks out.
https://memory-alpha.fandom.com/wiki/World_War_III