The ISW explained why the Russian Federation started shelling Ukraine with Shahed drones more often

Russian occupation forces continue to use Shahed attack drones and other less accurate systems to compensate for a significant shortage in the supply of precision munitions.
This is stated by analysts of the American Institute for the Study of War (ISW)
On the night of April 18-19, Russian troops launched 12 Shahed-131/136 drones over the southern regions of Ukraine from the Sea of Azov, 10 of which were shot down by Ukrainian air defense.
Russian pro-war bloggers recently discussed the importance of defeating Ukrainian air defense assets, even before possible Ukrainian counterattacks. And the Shahed drone strikes were probably partly intended for this purpose.
The press secretary of the Air Force Command of Ukraine, Colonel Yuriy Ignat, said that Russia has used almost all of its strategic missile stockpile since September 11, 2022.
The Armed Forces shot down 750 out of 850 missiles during this period.
According to Ignat, Russian forces have switched to cheaper and less long-range options, such as guided air bombs, and have taken Kh-50 missiles out of storage for refurbishing.
Analysts note that Yuriy Ignat was referring to the Kh-55 air-launched cruise missiles of the Soviet era, since the Russian Federation is due to start production of newer Kh-50 cruise missiles in the summer of 2023.
Russia may be removing Kh-55 cruise missiles from storage to upgrade them for future strikes on Ukraine.