Based on the history of the Russian Navy, and the state it was in even before the war, I would say the real damage to the Russian Navy has always been done by the Russian Navy.

Although Ukraine has definitely been destroying what little is left. I especially like how ever boat that’s hit is always “in for repairs” so it “was of no strategic value to Ukraine” even though statistically speaking every Russian ship is always in for repairs… since the don’t exactly work.