For about two-three months the Russians are using a new 'hack', their own version of the US JDAM- the UMPK. This low cost module converts unguided 500KG and 1500KG bombs into precision guided glide-bombs that can be fired from fighter aircraft up to 50KM away. Over the past two months they have scored a lot of successes with these bombs, and Ukraine claims that they use 20 UMPK bombs a day on them.
The 500KG bomb is 250 times cheaper than a cruise missiles & PGMs and the UMPK costs only $25,000 USD to manufacture. There is also a large arsenal from the Soviet era that can be used.
This development comes in time as Ukraine's air defense systems are running out of ammunition, 89% of their batteries use S-300 rockets and these are estimated to be depleted by the first week of May 2023.
It appears that the Russians intended to upgrade the UMPK to 3000KG and even 5000 KG bombs.
Literally if the Russians manage to mass produce these UMPK and upgrade all unguided bombs used by their fighter-bombers they can now blow up cities and military targets in a cheap and more effective manner than the old mixture of expensive cruise/ballistic/PGMs, unguided bombs/rockets, and high volume heavy artillery fire.