I guess you have a point about USB 3.2 being 1.5A (<1.6A) but not every laptop has this, in fact, the majority modren laptop does not restrict this current. In comparison, ancient laptop can’t even draw 1.2A before cutting of on the USB (2.0 IIRC) port.
Here are two other, one popular(Lenovo) the other niche(Panasonic), computers’ USB-A outputs connected to a power bank. As you can see on the Panasonic, the USB-A port can deliver 2A to the power bank, while the USB-C to USB-A outputs 1.7A(higher than 1.6A cutoff on the Framework) mainly because too much internal resistance of the many connectors. On the Lenovo, the USB-C to USB-A can deliver sustained 2A. They are all higher than the outdated specs on the Wikipedia link.
Before saying “voltage too low the port is overloaded”, I would explain that I was using a crappy cable with high internal resistance, as shown below, when doing 3A the source is 4.8V while the sink is 4.3V, thus when doing 1.5A the source voltage is about 4.9V to 4.95V, well before overloading.
0.9A @ 5V that’s USB 3.0, not even USB 3.2 standard(which is 1.5A), as shown in your linked thread the data speed is also USB 3.0. It might because of negotiation, i.e. might deliver 1.5A when negotiated 3.2. However since 3 & 6 is not PD and can’t receive any power, it’s more likely that 0.9A is hardware limited, unlike the software limited on the ports of FL13