That's exactly it - Polish version of the Agcat.
No, it really isn't. It was a M-18 Dromader, which is nothing at all like an AgCat. An AgCat is a biplane, where as the Dromader is a monoplane, and much larger with a much larger capacity. The Dromader was originally a product produced as a license copy by Thrush, in Poland, but was highly modified and has a completely different wing, significant fuselage changes, a bigger hopper and powerplant, different landing gear, tailwheel assembly and flight controls, and a different empennage.
The Dromader is the most common firefirefighting aircraft globally, particularly among Single Engine Air Tankers. I flew one for seven years, doing firefighting. it's a solid capable airplane.
It's been somewhat outshined today by the Air Tractor AT-802, and where I carried 650 gallons of fire retardant in my Dromader, I carried 800 in the Air Tractor. The air tractor is faster. The Dromaders I flew were refitted with turbine engines, rather than the russian and polish radials, and had different fire gates and hopper modifications, but were the same airframe and wing.
The M18B flies like a completely different airplane,with bigger ailerons, far more response, flap gap seals, etc. The Dromader, like many ag airplanes, isn't really "user-friendly," but it's a nice flying airplane as ag aircraft go. Heavy on the ailerons compared to an Air Tractor, but very nice compared to other aircraft.
It's definitely NOT an AgCat.