If a nether portal is created in the End using commands, ender pearls will pass through the portal if the player hasn't seen the end credits.

To reproduce:

1. Go to the end in a new world where the player hasn't seen the credits
2. /setblock ~1 ~1 ~ nether_portal
3. Throw an ender pearl into the nether portal
4. Notice that the ender pearl goes past the nether portal rather than going to the nether as expected
5. Jump into an end portal to see the credits
6. Go back to the end
7. Throw an ender pearl into the nether portal again
8. Notice that the ender pearl goes into the portal as expected

You may need to try throwing ender pearls into the nether portal multiple times due to MC-196556.