I'm using a permaloader contraption sending a minecart through nether portal and back.
Starting from 20w28a the cart comes off the opposite side of the portal.
But fixing the side of the portal the receiver/returning contraption faces doesn't fix it.
Since the cart stops moving and doesn't get on the powered rail when it portals back to the overworld.
Tested and working in 1.15.2, 1.16.1, and 20w27a (same world, upgrading it from version to version)
It's only on 20w28a when the portal and carts works differently
Attaching the 1.15.2 world which works, even upgrading to 1.16.1 and 20w27a.
And the modified version in 20w28a, which shows the cart stopping (just remove the stuck cart and add another to the dispenser).
There's a "workaround" adding a second minecart to the aparatus, since when it returns to overworld it pushes the original one forward.