I have this command that's supposed to teleport players when they reach a specific point on the x axis (regardless of y or z), for some reason it teleports everyone regardless of their position on the x axis
Here's the command - execute at @p[x=-5371] run tp @p[x=-5371] 5365 ~ ~
It's running on a custom data pack as a loop for each tick
It doesn't work like that. You cannot use x= alone in a selector, (x= and dx= must be used tgt; whereas dx is known as the volume selector). Also, you are scanning for the nearest player only and I would suggest for you to use @a which perform the task for all players.
To further elaborate, the volume selector takes resemblance to how you use the fill command, where you will enter the coordinates of the starting point and ending point respectively and the game will calculate the volume and the blocks affected depending on the points you entered, allowing you to fill an entire space with blocks of whatever kind. Similarly, working with the volume selector requires you to fill in 2 parameters, the starting coordinates (x=,y=,z=)
and the coordinate displacements (dx=,dy=,dz=).
Suppose starting coordinates (x, y, z) Then ending coordinates = (x+dx, y+dy, z+dz)
This allows the game to draft a volume (block region) and evaluate the player position to see if it matches the volume.
An example:
To test for players at point (x=64, y=64, z=64) use the command
execute as @a[x=64,dx=0,y=64,dy=0,z=64,dz=0] run say DetectedPlayer
This draws a block region of 1x1 at point (64, 64, 64) and if the feet coordinate of a player lands in its proximity the player would say in chat "DetectedPlayer"
Albeit I really am not sure if you can have an infinitely extending volume of block region.
I interpret your question as how to set a border for players. In that case I recommend you to use /worldborder which is way more user friendly and conventional```
Here is the page you are looking for if you are hell bent on using the volume selector https://minecraft.fandom.com/wiki/Target_selectors
