Yeah, that cylinder could have gotten pretty hot at one point.
I swiped the service history on this car so I know the #2 injector was replaced because of the P0302 code. It may have been replaced based on "let's try it and see if that helps" or it may have actually be tested and found NG.
Its pretty much impossible to know for sure what caused it with the resources that I have. But the injector idea makes the most sense.
If it was a clogged injector I imagine this issue could be more and more common as the LGTs get up there in mileage. The owner of whichhunter said he has never once come across a bad yellow-top bowl-fed injector from a subaru but they can get clogged just like any other injector.