Pixel 6 might not charge with just any old cable
The Google Pixel 6 doesn't come with a USB-C adapter in the box. You get a USB-C-to-USB-C cable but not the box, and that might cause some charging issues. Reports claim that some Pixel 6 owners have charging troubles with incompatible USB-C cords. A user posted in a Google forum back in October saying that when they used an old charging cable that "Nothing happens." The user wrote, "No charge, no warning, no nothing. It's like it's not connected."
A Google Platinum Product Expert instructed the user to buy a USB-C cable compatible with the Pixel 6's fast-charging USB Power Delivery specification. The company suggests using a USB-C cable with a USB 2.0 power adapter at minimum instead of the USB-A one. Because the latter might charge your phone slowly or not at all. This might defeat the original intention of being more eco-friendly, but it is what it is. If you're wondering why you're running into a charging problem, this clarifies things a bit.
Source: Gizmodo