Official site (in French🇫🇷): https://www.4joursdedunkerque.com/ledition/
PCS page: https://www.procyclingstats.com/race/4-jours-de-dunkerque/2025
Usually, no substantial differences can be made on most stages and they end up in bunch sprint.
Only Saturday's stage has been deemed worth broadcasting on national channels in France. This Cassel stage include a circuit with 2 main climbs: a steep one and a cobbled one. It is pretty similar to the circuit that was used for the National Championship of France in 2023, which was pretty hectic. Saturday's version of the circuit will a little bit longer, I don't know if this makes it easier or harder. Anyway, it will be ridden about 6 times, versus 15 during the Championship.
All Tiz videos of this Championship are down, so here is a 10 mn official summary (comments in French).