Bosch ebike spider problem

[All uphill]

My son's Carrera has a Bosch Active Line motor. He's just stripped and resprayed the bike and on his first ride the spider stripped.

The teeth on the motor are undamaged thankfully.

Anyone have any thoughts about what may have happened?

 

[Saluki]

Spider stripped on my partner’s Moustache too, that has a bosch motor too. He’d had the bike maybe 8 months when it happened. The Moustache dealer replaced with no fuss whatsoever.
The spider on mine is, so far, just fine.