Why Didn't Russians Use Drones?

There were a lot of videos that they predominated in the early weeks of the war showing Russian convoys just rolling blind into ambushes with anti-tank weapons. The obvious question to ask was, well, why weren't they using drones? And especially after Nagorno-Karabakh, I know there was some resistance in the Armenian and Nagorno- Karabakh upper ranks to the importance of drone. Russia went into the war with about 2000 or so UAVs,. all UAVs, all classes. That wasn't enough because they started losing them at a significant scale and a significant rate.