Banks 1 and 2? That suggests you have two catalysts, two pre cat sensors and two post cat sensors. The chances of both catalysts having failed together are slim. More likely you only have one catalyst and two sensors, one before and one after.

The catalyst works by chemical reaction. It needs carbon monoxide and oxygen for the chemical processes to work. The engine therefore needs to run both rich to produce CO, and lean to produce O2. If the engine is running as it should be the catalyst converts the harmful gasses into non harmful gasses. The post O2 sensor merely tells the ECM that the catalyst has worked, or not. The ECM does not respond to the information received from the post cat sensor by altering the way the engine runs unlike it does with the pre cat sensor. Your garage needs to check the engine live data and the fuel trim readings. If all of that is good then the catalyst might be the problem. If the engine is running poorly and the ECM is taking corrective action which goes outside its parameters then a fault code relating to the pre cat O2 sensor is likely to be generated.

P0420 'Catalyst Efficiency Below Threshold' will be stored if the two sensor readings are too similar, indicating that the catalyst is not working.

the Rav's have 4 sensors, and they have a habit of failing in turn, one after the other.