Looks like a dealer installed 'alarm system'. I bought a mazda in 2011 which had a similar system, as best as I can tell the dealer installs them as asset track

Looks like a dealer installed 'alarm system'. I bought a mazda in 2011 which had a similar system, as best as I can tell the dealer installs them as asset trackers for cars on the lot and then tried to upsell it to me as an 'alarm system'. Its a bit sketchy that they didn't mention it to you when you bought the car... The 433MHz is likely a keyfob receiver (and possibly transmitter to spoof the original key).