The previous answers gloss over an important point - they're vague about what's actually driving this. Sure, funding and technology help, but what's really changed in recent years is the legislative requirements for archaeological monitoring. When a road is being built, a pipeline laid, or a tourist zone developed, preliminary surveys are now mandatory. These requirements used to be much looser, so mounds were simply destroyed during construction or just ignored.
Plus, regional tourism has become economically profitable. Mounds, especially those with Scythian and Sarmatian artifacts, are unique content for tour routes and museums. Regions are interested in excavations not just for academic reasons, but as a way to attract tourists and secure federal funding. It works as an economic incentive.
And yes, technological advances really do make the work easier - ground-penetrating radar lets you understand what's inside a mound without unnecessary digging, drones speed up surveying and documentation. But without the legal framework and economic motivation, these technologies wouldn't be applied on a large scale just like that. The surge in activity isn't a fad - it's a combination of several pressures hitting at once: legal, financial, and technological all together.