You could split the field by using the .split() option, So something like {{ $json['text'].split(',') }} would split the text field on the , and give you an array.
TypeError: Cannot read properties of undefined (reading 'every')
at Object.normalizeItems (/usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/src/NodeExecuteFunctions.js:867:23)
at Object.execute (/usr/local/lib/node_modules/n8n/node_modules/n8n-nodes-base/dist/nodes/Function/Function.node.js:97:34)
at processTicksAndRejections (node:internal/process/task_queues:96:5)
at async Workflow.runNode (/usr/local/lib/node_modules/n8n/node_modules/n8n-workflow/dist/src/Workflow.js:598:28)
at async /usr/local/lib/node_modules/n8n/node_modules/n8n-core/dist/src/WorkflowExecute.js:557:53