Earthing Plastic Dimmer with Meta Plate Inside

Apologies in advance for this very simple question...

I understand that if a dimmer switch plate is metal it must be earthed. I am replacing one plastic dimmer switch plate with another. However, on the inside of the face plate there is a metal plate which the old switch did not have. (Apologies, I can’t figure out how to add a picture)

Does this then need to be earthed? Or is it fine without?

Many thanks for any help in advance.

What do the manufacturers instructions that came with the switch say?

Have they provided an earth terminal on the light switch?

If it needs to be earthed it will have a marked earth connection.  If there isn't one and no different advice in the instructions then leave it alone.   (May get hot in use so don't tape over or let cables press against it) .
 

(Just because a dimmer heatsink (internal / inaccessible in this case) is metal it doesn't have to be live - in fact having it live is daft in so many ways.)