This (and the absence of any earlier errors on the endpoint) looks
like the hardware may be confirming a "successful" transfer twice or
the driver may be processing one such confirmation twice.

[   94.088594] usb 1-2: USB disconnect, device number 8
[   94.089370] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 1 comp_code 1
[   94.089403] xhci_hcd 0000:00:14.0: Looking for event-dma 00000001250310f0 trb-start 0000000125031100 trb-end 0000000125031100 seg-start 0000000125031000 seg-end 0000000125031ff0
[   94.089427] xhci_hcd 0000:00:14.0: last xhci_td_cleanup: first_dma 1250310f0 last_dma 1250310f0 status -115 from finish_td

(I say "successful" but it really isn't - the device is no longer
listening. But there is no delivery confirmation on isochronous OUT
endpoints so the xHC doesn't suspect anything.)

Could you try again with this updated debug patch to get more info?

Regards,
Michal