Hi
It’s not to say that all of these models are poorly designed, if you look at the photos it clearly shows separation with the timber not the glue join so what I am trying to say is that the timber in this case was of poor quality the glue did not give way at all and the plane was flown around half throttle at the time with no high stress.
I suppose you have to see it in real life to get the picture and there is no other story to be told at all.
It could be one in a million but it doesn't detract the fact the fault is in the timber and in this case shows no delimitation of the epoxy glue at all.
Best regards