Version

3.2.31

Reproduction link

sfc.vuejs.org/

Steps to reproduce

1. Create a SFC with a single root node.
2. Assign a template ref to that root node
3. render app with "renderToString()"
4. The output generated code has a "ref_key" property.

What is expected?

The generated HTML should not contains any internal property used by the code generator

What is actually happening?

The generated HTML contains a "ref_key" property

This only happen if the SFC has a single node where the template ref is assigned.