World border

If you set the world border to something like 10

teleport to the nether using;
/execute in minecraft:the_nether run tp @s ~ ~ ~
And if the nether is not generated yet it would glitch the game and setting the world border to its old size wouldn't fix it

The way to fix it:

• Teleport back to the Overworld
• Fix the World border
• teleport back to nether