Hi Patrick,
Sorry for the delay.
We have prepared simple Prism sample with SfAccordion. In this sample, we have placed the SfAccordion control at middle. But we are unable to reproduce stretch issues in this sample.
Please download the sample from the below link.
If the issue still persist, could you please provide more information like screen shots or reproducible sample. It would be very helpful for us to resolve your problem at the earliest.
Regards,
Mariappan S.