Has anybody come across a workflow that kicked off without any starting rules, business processes or invoke workflow activities?

I have a scenario where we designed a workflow to rerun forms processes in 2019. Over the weekend this workflow kicked off again and caused email to be sent out which caused duplicate process to occur.

I cannot see who started the workflow as the originator only shows "String Content".

Does anybody have any ideas as to how I can investigate this occurrence so that it can be stopped from happening again?