After updating my Z Flip 4 to version F721BXXU1BVL9 / F721BOXM1BVL9 / F721BXXU1BVL9, the device doesn't charge (neither wired not wireless) while flipped close.
When the device powered on and is plugged in before being unfolded, the battery indicator in the top right flashes on and off. A temperature warning also occasionally occurs when plugging in the device right after flipping it open.
The only way to get it to charge is by powering off the device, after which it can be charged wirelessly (albeit extremely slowly). The device does charge when not flipped. I found a Reddit post mentioning a very similar issue, but the OP mentioned he sent it back to Samsung and got the LCD replaced. I'm however assuming it's related to the latest software update, because the issue occurred the night after I installed it.