[Vapor] Fallthrough class and style updates can overwrite a component root’s own values

Vue version

3.6.0-rc.9

Link to minimal reproduction

https://play.vuejs.org/#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

Steps to reproduce

Click the button.

What is expected?

Should retain its original attributes

What is actually happening?

The original attribute has been deleted

System Info

Any additional comments?

No response