Weird Immense Cave Spawning

Ok so in bedrock edition 1.17.41 if you make a new world and the seed is "nan" you will spawn at a beach. You will see a weird cave. No big deal, So you hop in. THEN ITS LIKE SPAWN TO THE DANG WORLD BORDER!

Recreation-
Step 1: Make a new bedrock edition world with the seed "nan"
Step 2: You will see a big cave, Hop into this cave
Step 3: Explore the cave
And you did the glitched seed