The first Raspberry Pi 4 boards suffered from a poor USB-C power supply compatibility due to issues for the power circuitry. That means if you bought the official USB-C power supply you had no issues, but if you wanted to re-use a spare USB-C power supply or incompatible cable, you may be out of luck.
The Register is now reporting that the Raspberry Pi Foundation has discreetly released a new revision (v1.2) of the board that fixes several issues including USB-C PD compatibility, and as Eben Upton explains the new revision also:
moved the WLCSP SD card voltage switch to the top side
… silk screen tweaks to reduce solder bridging in manufacture”.
The new boards have been around for a couple of months as some users report the USB-C power issues have been fixed on new boards.