Comment by lxgr

Both my current M1 Mac and my previous Intel Mac were fine with the cable!

> It would be interesting to know of a high quality cable tester showed some other difference in capabilities between the cables that may explain it.

I'm fairly certain that the cable itself is perfectly fine, but that the iPhone insists on a specific bit being set on the e-marker chip insider the cable, while Macs are more tolerant and will just attempt a USB 3 connection anyway, especially since they need to support unmarked USB 3 for use with USB-A adapters anyway.