I received a similar response to @Volvox_Globator from Bambu support.
Bambu support thinks it’s the chamber heater actually heating the bed on the corner which causes the twist is you may notice is starts as soon as the bed frame reaches the top of the heater. If you measure the height of the affected area it roughly matches the Z height of the bed itself as well.
Running the modified gcode isn’t really a proper or effective fix and tbh I don’t think it is fixable without possibly re-directing the chamber outlet with a cover so it doesn’t hit the bed directly.
The chamber might stay hot enough for a little bit after it’s been turned off but you will likely see a different rate of shrinkage from the height it turns off which results in some inconsistent layers towards the top, it’s just not quite as drastic as having the heater on the whole time.
I’ve also found printing ASA without a heated chamber tends to result in cracked ASA/ABS prints after a couple of hours. My guess is because the chamber is larger than the smaller machine models so it doesn’t get to as high a temperature without the heater.