Typical issue of ESCs with two shunts only, like VESC 4.xx and Focboxes, Unity etc.
These can’t sample the current far away from the switching cycle. In consequence the ESC does not respond linear to throttle inputs. They jump from 80% to full throttle and there is nothing you can do software wise to compensate. On powerful, torque rich, heavily geared boards that is very noticeable and can cause trouble like you described.
There was a reason why Benjamin Vedder went for three shunt designs after the VESC 4.12.