I think what’s happening is that when the power bank detects the cable is EPR enabled, outputting fixed power of 140W, the Framework 16 Embedded Controller ( part of the BIOS ) is trying to negotiate with the power bank using EPR + AVS, but it fails because the power bank ( output only ) doesn’t support AVS, and the FW16 retries after some delay ( I think approximately 1 seconds ) repeatedly until you unplug the power bank
Interestingly, I tested the PD protocol support with my 2 devices mentioned above, of which one works with 140W. Here are the results:
Powerbank (works with 140W):
Fixed: 5V 3A
Fixed: 9V 3A
Fixed: 12V 3A
Fixed: 15V 3A
Fixed: 20V 5A
PPS: 4.50-21.00V 5A
EPR Capable
Fixed: 28V 5A
Charger (does NOT work with 140W):
Fixed: 5V 3A
Fixed: 9V 3A
Fixed: 15V 3A
Fixed: 20V 5A
PPS: 5.00-11.00V 5A
EPR Capable
Fixed: 28V 5A
AVS: 15-28V
I’ve highlighted the differences. So, based on the results of this USB-C tester (Power-Z KM003C), the device which supports AVS is the one that does not work properly, while the device which only supports EPR with fixed voltage 28V, does charge it at high wattage.
So I’m not sure if the results are similar with a different power bank, and I can’t be 100% confident of these test results, but from these, it looks like the AVS would likely be the problem, as it works with the powerbank which does not support AVS but only supports 28V fixed voltage with max 5A.
As for the mentioned concern - how the laptop could charge with fixed setting in case the battery is already full - that should not be a problem, as only the voltage part in the protocol is fixed. Current is still being drawn only as much as needed/supported. Once the laptop is charged, it would either limit the current (amps) drawn at the same voltage, or possibly renegotiate to a lower voltage. With proper support for AVS, the device can constantly tune the voltage as well, in small increments, to provide the maximum efficiency or charging speed.
Therefore, I assume there is something wrong with the negotiation when using AVS. However, I’m unable to confidently say if this is on the side of Framework or the side of Anker charger (140W port), because I don’t have another AVS capable sink device to test on - the power bank charges at 140W, but also seems to use fixed voltage for charging.