Where is this XML from? Did you create it manually? Why would you want to have no prefixes? start_mode wouldn’t be part of the default namespace of BPMN so you’d need to use a prefix to indicate that. This is how XML works.
Thanks @philippfromme . This XML structure is the historical data, the current use of BPMNJS access, need to be compatible with the historical data. The most conceivable solution is to use string matching with label substitution for preservation.