Easyjet was in PIK yesterday too, and Jet2 were doing circuits all day on Tuesday and yesterday too.
PIK is a very popular airport for aircraft base training with many airlines. Base training is when pilots newly trained on a new type of aircraft do their first flight on the real aircraft and perform a minimum of 6 takeoffs and landings (or touch and go) until a training captain is satisfied that they are proficient at it.
Base training has very benign weather requirements (VFR, little crosswind, etc) so on days like today and yesterday PIK was perfect, combined with quiet airspace, a long runway and probably competitive landing charges. PIK is only one of 2 airports that FR uses for base training these days (other being EMA). Others like Shannon in Ireland are popular with many airlines too for the same reasons.