Killing usbd
On the rare occasions that I plug my iPhone into my computer (a 2015 MacBook Pro), the phone will usually connect and disconnect rapidly, buzzing every couple of seconds as the phone is discovered and undiscovered, not charging. Most SEO-optimised posts online ask you to reset your System Management Controller or completely format your phone, which is not practicable. Instead, I've found that restarting the usbd service fixes the issue. You can do it on the command line but I've found it easier just to open Activity Monitor, search for "usbd", and kill it from there.