(Unsure if this is can be considered a bug or not)

To recreate:

Create a single biome (Jungle, sparse jungle, or bamboo jungle) world with the seed 2845176783615296641

Run the command /locate ruined_portal (It generates consistently regardless of seed)

Observe how the ruined portal has leaves on it

Now, go back to step 1, but use a different biome (such as plains)

Notice how the portal is both submerged underwater and without leaves.