The feel rule matches any property that starts with = regardless of whether this property can be a FEEL expression.

<bpmn:serviceTask name="==5" />

will lead to a report that name is not a valid feel expression.

A possible solution could be adding metadata to the camunda-bpmn-moddle extension.

Example:

{
  "name": "InputOutputParameter",
  "properties": [
    {
      "name": "name",
      "isAttr": true,
      "type": "String"
    },
    {
      "name": "value",
      "isBody": true,
      "type": "String",
      "meta": {
        "feel": true
      }
    },
    {
      "name": "definition",
      "type": "InputOutputParameterDefinition"
    }
  ]
},

We'll have to investigate whether this works for all FEEL properties. Alternatively, we could have a list of properties that are supposed to be linted.