Lexus GX exhaust leak rough running

Sounds like an exhaust treatment malfunction. Any recent work on the exhaust pipe? Could be faulty NOx sensors or a bad oxygen sensor. Is it burning DEF fluid, or is the exhaust leak closer to the engine than the tailpipe?

No DEF fluid usage, and the exhaust leak seems closer to the engine. Could you elaborate further on the oxygen sensor and how to check?

With the leak near the engine and no DEF usage, I'd lean towards a faulty lambda/oxygen sensor. You could try some DIY checks, but proper diagnosis often needs specialized tools to read the sensor data. Rough running and the smell suggests it's messing with the fuel/air mixture. Honestly, best bet is to get it to a workshop for a proper diagnosis. Could save you money in the long run.

Took your advice and brought it to a workshop. It was indeed a defective lambda sensor. Repair was 375€.