Two weeks before the war started, the Moskva's readiness report was leaked on line. The ship was barely seaworthy. The engines were past their service life, the air defense except one CIWS didn't work. The control systems were worn out. The entire class was built as a safeguard if the Kirov class failed, so they were built big and cheap, including damage control.
From what I can tell, she was hit three miles off shore while on a shore bombardment mission, without escorts. Even if her air defense worked perfectly and were updated, they would still have problems on low altitude air targets over land since the land mass creates lots of radar horizons and background problems. The Russian Navy was so overconfident they did not try to screen the most obviously vulnerable and high value asset they had, on a shore bombardment mission another ship could have done, if the mission was worth it at all.
Before she was sunk, on April 3, 2022, Ukraine successfully used a Neptune anti-ship missile to attack the frigate Admiral Essen. Another Russian warship close to shore was fired upon using a BM-21 and a transport sunk in harbor by a ballistic missile. The Russian Navy had to know that Ukraine was absolutely looking for any opportunity to sucker punch the Russian navy and had the means.
The icing on the cake, The Moskva was built in Ukrainian shipyards. They knew the ship and what condition she was in. A NATO reconnaissance aircraft was tracking her, and the Moskva had a regularly schedule maneuvers like clockwork, limited if any variability in her maneuvers.
Given all of that, what was the Russian navy thinking?