See https://www.zabbix.com/documentation/4.0/manual/api/reference/action/object .
It does not mention that pause_suppressed is only valid for trigger actions. Attempting to pass it for a discovery action results in:

Cannot set "pause_suppressed" for action

Other fields like esc_period, esc_step_from and esc_step_from might also be only supported for some action types (not supported for discovery actions, for example), although they do not seem to fail the validation currently. Nevertheless, it might be a good idea to document valid scope for all parameters.