The Raspberry Pi 4 promises to be a boon for homebrew gadget makers, but it has flaw that could pose headaches for some users. Tyler Ward and others have discovered that the Pi 4 isn't using a properly designed USB-C port. Instead of giving two pins their own resistor, Raspberry Pi created a custom circuit that has them sharing a single resistor. As a result, some USB-C chargers (those with "e-marked" cables) will only recognize the Pi 4 as an audio accessory and won't charge it.
That effectively rules out a load of high-powered chargers, particularly ones for laptops like Apple's MacBook line.
There is relief in sight. Raspberry Pi co-creator Eben Upton suggested to TechRepublic that the USB-C issue would be fixed in a "future board revision." In the meantime, though, you'll have to be choosier about powering the Pi. You can rely on non-e-marked cables, including the ones that come with many smartphones as well as the official Raspberry Pi option. Older chargers with USB-A to USB-C cables, or micro-USB to USB-C adapters, should also work if they supply enough power in the first place. It's not a calamity, then -- you'll just want to be careful if you're going to use a Pi 4 as the heart of your next DIY project.