It never really changed - the coast was, and always ever will be - at sea level!
While the weight of the ice does have some effect - the main issue is all of the water was up in the ice (world wide) so the sea level was low, and coastlines were low. Ice melts, sea level comes up and the coastlines move inland, putting a lot of the coastal settlements underwater. (Of course I’m guessing you knew that already).
The “rebound” effect of the ice is pretty limited. But it is still going on with minor elevation changes, and some oddball small earthquakes.
If you look at the line of red dots representing the settlements, you get a very clear picture of how much faster the land has risen than the sea level.