One of my shut off valve need to be replaced. It's a metal valve in a copper pipe.

A plumber proposed a solution, by adding plastic fittings on both ends of the valve.

The plumber said the finished project would be like this (from his previous job at another customer's). (see the fittings in blue circles).



I don't know a lot about plumbing code, so I'm seeking advice here. Is it a common practice to add plastic fittings like this?

I'm in Ontario, Canada. Thank you very much 😊