1 Dergach class corvette damaged in repairs
1 Dergach class corvette destroyed
4 active Dergach class corvettes
2 Dergach class corvettes will enter service
= 4 active corvettes, 1 under repair, 2 will enter service and 1 destroyed
There were only two such Project 1239 ships made. Are you confusing this with something else? This is a Yeltsin era project and there is little chance of more ships being built.
Also, your chart shows the Admiral Makarov as being hit by Ukraine. Yet there is zero evidence of this having happened. Ukraine attacked it, but it was undamaged and none of the drones hit.
There was one irrecoverable loss of a Ropucha class ship when it was hit with a Tochka missile while in port and it sank.
Another of the Ropucha class ships they did damage has already been repaired and put back into service.
Another Ropucha that Ukraine damaged was announced to be currently under repairs. The Russians said they will remove the upper structure, and replace it with the upper structure of another inactive Ropucha class they captured from Ukraine when they annexed Crimea. They also said they will repair the submarine hit in dry dock and the corvette hit in port. But we will see. I kind of doubt it since the damage looked quite extensive.
Overall: 52 boats/ships/subs likely active, 10 undergoing repairs, 4 entering service and 8 destroyed. Even if we put all the boats/ships/subs under repair and destroyed due to Ukrainian action(which is actually not all although it is the majority), out of a total of 70 naval units, 18 were affected, a total of 25% of fleet that was in the Black Sea.
It is normal for a navy to have a third of its ships out of service at any one time doing maintenance. So 25% of the Russian Black Sea Fleet non-combat capable isn't that high of a percentage. The rule of thumb is one ship at sea, one ship in port, and another doing maintenance. The reason for this number being this low in the first place (25% and not 33%) is likely because of a large chunk of the fleet like the submarines being relatively new.
The loss of amphibious ships is hard to replace since those ships used to be built in Poland and there is no project to replace them yet. One was sank for sure, one was damaged and later repaired, and another was damaged and is being repaired. There is the Ivan Gren class of ships, and the LHDs, but those aren't exactly the same class of ship since they are much larger.
The loss of the Moskva was a major blow but the ship was basically obsolete. It has about the same number of surface attack VLS cells as an Admiral Gorshkov class frigate, and while it carries more SAMs, those either use a revolver launcher, or a dual arm launching system, so it can't handle saturation attacks properly. They lost the Mosvka, but they put the Admiral Golovko into service which is about as capable if not more despite having like a third of the displacement.
As for the other ships, Russia can basically replace them with more modern ships at least as fast if not faster than the Ukrainians can damage them.
I think the naval drones thus far have proven to be more of a nuisance than a real threat. They only seem to be effective against really small ships. The large ships all seem to have been damaged with cruise missiles. In theory the drones could be quite dangerous, basically a cheap torpedo, but in practice they are slow and very visible. In nearly all instances we see that Russia manages to detect the drones and fire at them with deck side machine guns.