Ukraine a few days ago declares that they hit Russia's sub using Russia's base's CC-TV to guide the underwater drone.
Russia shows a photo of a blown up dock but the 3 other subs in the base are scattered except the one Ukraine claims to be hit.
Higher def photos today show the sub leaking oil and listing in the water. It's shown to be out of commission.
Russia protects the rest of the Black Sea Fleet by sinking barges at the entrance of the base trapping the bulk of the Black Sea Fleet in the base.
Other than the 3 missile subs, most of the Black Sea Fleet has been retired for this war. Now they are simply targets for air drones/missiles.