An array of arrays gets translated into List[List[T]], even when the second array has contraints, losing these constraints. Minimal working example :

{
  "components": {
    "schemas": {
      "Mod": {
        "type": "object",
        "properties": {
          "prop": {
            "type": "array",
            "items": {
              "type": "array",
              "items": {
                "type": "number",
              },
              "minItems": 3,
              "maxItems": 6
            }
          }
        },
      }
    }
  }
}

I see 2 solutions to that :
1 - Use a conlist to keep the contraints. Albeit compact and easy (only a few lines to add around datamodel-code-generator/types.py L87,L254 and datamodel-code-generator/parser/jsonschema.py L772), it would stand out quite a bit, compared to the rest (the conX objects being alone in their own Item model).
2 - Handle constrained array the same way object is handled: by giving it its own Model, which would allow to store the constraints in Field, as it is done for a single array.