What I expected:
To emerge from the portal, and when the chunk loads, I expected my feet to be placed on the ground.

What actually happened:

• There might be a 'falling into the void' visual effect, (pretty common, but isn't the issue here)
• After that, once the chunk I'm in is completely loaded, and the ground is present, at that moment I expect my feet would be placed on the ground.
• Sometimes I am placed a noticeable height above ground.
• Other players can see my character 'drop' from that small height as I emerge.

It doesn't do this every time, and so far I can't find a pattern.