The reason this is significant, besides being an enormous loss of difficult to replace aircraft, is that it was so far from the front lines. Russia has been fumbling in the last month to adjust to western HIMAR weapons that have been precisely targeting ammo depots, hqs, and other high value targets far behind the front lines. Russian logistics is largely train based. They ship everything by train and unpack it to a nearby warehouse, then rely on trucks for the last mile. The HIMARs have been destroying the warehouses, meaning Russia is now needing to use trucks for much much more than the last mile because they can't unpack everything near the front. This new strike is even longer range than the weapon specs Ukraine was believed to have. And it was 2 very precise explosions. How this was achieved is not clear, but if Ukraine now has frequent precise missile capabilities for 200-300km strikes, that means Russia may need to scramble their logistics all over again.
Right now the most important location in the war is Kherson, occupied by Russia. It's the only truly valuable asset that Russia has seized, and recent Ukranian advances have made Russia pull 20-30k troops off of other front lines to reinforce this area. It's a very difficult position for Russia. There's just a couple bridges leading into Kherson from the south (Russia / Crimea side) and Ukraine has been blowing them up. Logistics of supplying those 30k troops is going to be really tough. And now Crimea, the main logistics hub for those troops, is appearing very vulnerable.
Ukraine's goal here is to make the defense of Kherson extremely resource intensive, meaning Russia has to either lose the territory or weaken up on other fronts.