Korvetter versus fregatter

The Frigate is the smallest class of ship that has an independent commander. A corvette is under direct operational control of the admiral placed on land.

This means that the corvette can be lighter manned, than the frigate. The crew does not need to be stationed at sea, because the corvette is rarely away from port very long - and as such the crew can be rotated with another crew.

But when it comes to firepower the corvette is as potent as the frigate in anti-submarine warfare, air-defence and anti-surface systems.

If it is for coastal defence it does not need the speed of a frigate. Simply because in shoaling waters the speed is limited anyhow. This means the power demand for propulsion is vastly deminished. The engine power requirement of 30 knots is halved if you can manage with 24 knots.
The old danish Daphne class patrol boat was grossly overpowered in the sense, that at full power it only produced waves and cavitation (which is destructive to the propellers) - it would have performed equally well with half the power installed.

Now the use of a corvette in port is that it is the air defence of the port, so only the air defence postings need to be manned at all times. This is because a port needs a point defence.

Now obviously the russian admiral did not get the memorandum concerning naval warfare. That is believeable The corvette should have been firing its missiles and guns at the incoming drones and Storm Shadows. But no: Apparently the ENTIRE crew was on vacation.
Let me remind you, that during the attack on Pearl Harbor the japanese suffered heavy losses in the air - all due to the AAA on the battleships.
Please note: The fourth Ford-class carrier is to be named after Doris Miller. He was a mess attentant (cooks had combat stations at the Anti Aircraft gun - at the battle of the Coral Sea - I believe it was - the AA gunners asked the chief to cut the power to the ovens as the bread was about baked).

There is a conceptual and organsatorial difference between a corvette and a frigate.

A frigate is the lowest independently commanded ship. The corvette has the same firepower as a frigate; but the admiral is sitting in land headquarter. On a frigate the command has been handed to the captain.

What a corvette does not have (compared to a frigate) is endurance at sea and speed through water. Which means that for a similar firepower the corvette can be build smaller:

a) It does not need facilities for a second crew to relieve those coming off shift.
b) A corvette does not need the fuel for long streches of transit.
c) A corvette does not need the engine power to catch up on the ocean. Partly because the corvette is a "brown water" ship that sails in predominantly shoaling waters of coastal areas (like the Baltic or the Black Sea). Increased power does not mean greater speed, as that only sucks water under the wessel away (the Venturi-effect) making the vessel settle deeper into the water - giving increased frictional drag (beside the risk of running into undersea obstacles like recently submerged enemy ships and mines - possibly sunk ships (very relevant bother in the Baltic and the Black Sea). Besides being close to the admiral means that they don't sail very far to reach operational area - so speed is not that important).

Now what is happening in the Black Sea is that: As the ukrainians sank the Moskva, they actually gave up the idea of an independent Black Sea Fleet, as a high sea fleet - though if the Mediterainian is "High Sea" is a moot point.
Ben Hodges is a great general. Oh the Ukrainians have a NAVY, but it is a coastal navy. Ben Hodges has never pretended to be an admiral.

See what the oldest and most experienced navy in world is doing: The Royal Danish Navy. They have in their 5-600 years of existance with both the North Atlantic and the Baltic a basic naval problem - and they might have learned a trick or two.

See what the RDaN does. It build the Huitfeldt-class with its extreme range, comfortable crew quarters and 30 knot power by 4 diesels. The ships can run at Fleet speed on one engine, Patrol speed on two or War emergency power on four engines - saving fuel and giving a range that is double that of an american ship.
Now they are planning a class of corvettes with a top speed of 25 knots for the Baltic.