Clearly looks like a frame defect. And yes, could be done by jumping from a 3rd floor to flat while weighting 200kg, but I'm not so sure it could be done in the real life ;). BTW. I broke 3 alloy frames and 2 times they where replaced without any issues. 3rd time was clearly my fault, since it...
Shimano is going to release an updated motor this year, probably it will fit to current bike frames. Also with Bosch you would not be able to offer a custom battery as here. So for some manufactures it is easier to go this way - and for us the most important thing is to have a choice.