I have a Gravely ZT XL 42" bought new in 2020. If I idle for more than a minute while opening a gate for example, there will be a round burned grass area. It just started happening in June of 2022. I can't tell that any heat shield is missing. But it seems to be from the exhaust. Tested on an out of way area. Left idling for five minutes. The next day there was a round burnt area.