The plane going in circles above my head for an hour now, what could it be?
The vertical profile matches that of a plane staying in the pattern doing touch and go landings or practice approaches.
The airport doesn't show on the maps of the flight tracking websites, since it doesn't have a 3-letter IATA code I suppose, but from Google Earth the airport is HAL Airport (IATA: HAA128, ICAO: VOBG), at an elevation of 2,912 ft. The one dip to zero has to do with how FR24 processes if the plane has landed; FR24 doesn't show height above ground.
From 2018, indiatimes.com reported that "At HAL Airport, pilots spread their wings":
Major domestic carriers such as Alliance Air, Jet Airways, Jet Lite, IndiGo, GoAir, Vistara, Air Asia and SpiceJet have been using the airport to train their pilots and crew members.
Similar to this: Why is this plane circling around the Lucknow airport every day?