When the card is issued that determines the expiry date. If you applied overseas you will get the Resident Authorization Form (basically a paper version of the card) to show immigration at the border.
Your card is printed and sits at the Immigration Center until such a time you collect it.
When I collected mine the agent at the counter looked through a stack of cards to find it.
To be clear, the expiry date is not counted from time of entry or pick-up.
I have checked my emails and expiry date and it seams to work like the below example:
Apply for 3 year duration Gold Card.
Received email on 2020-02-12 stating your application has been officially approved and is now entering the certification stage.
Gold Card expiry date will be 2023-02-12.
It took me a month from getting approved to entering Taiwan, though that didn’t change the expiry date.
Hope that helps clear things up.