Right to reside - deportation order

Hi,

Is it correct that a EU national, with a right to reside, continues to hold that status until such time as a deportation order is served. And it is the serving of the deportation order that invalidates any leave to remain in the UK
If this is correct: what is that national’s status if the deportation order is then withdrawn?
Does the national’s status then revert to what it was before that deportation order was served?
Or, does that national then have to establish a right to reside from scratch.
I may be thinking way above my pay grade but, isn’t there a potential abuse of process here?

I would welcome your thoughts, guidance, suggestions especially if you have had a client in such a situation.

Thanks.

ELC