My main Overworld "world" border radius is 5000 blocks, while the Nether "world_nether" has a border radius of 625 (5000/8). Traveling from the Overworld to the Nether using portals works perfectly, though whenever I try to cross an Overworld portal in the Nether, if it's located at an X or Z Nether coordinate past 625/8 (about 78 blocks) for some reason I get teleported to the Overworld at either X or Z equal to 625 (depending on which axis the OW portal in the Nether was past 78) and same Y as previously. Needless to say most of the time this leads to death/suffocation of the player.

What seems to be happening is that the portal is knocking players back in the overworld following the world border set for the wrong world (world_nether instead of world).

Here is my config.yml

cfg-version: 11
message: You have reached the Border of this world!
round-border: false
debug-mode: false
whoosh-effect: true
portal-redirection: false
knock-back-dist: 3.0
timer-delay-ticks: 5
remount-delay-ticks: 0
dynmap-border-enabled: true
dynmap-border-message: World Border
dynmap-border-hideByDefault: false
dynmap-border-priority: 0
player-killed-bad-spawn: false
deny-enderpearl: true
fill-autosave-frequency: 30
bypass-list-uuids: []
fill-memory-tolerance: 500
prevent-block-place: false
prevent-mob-spawn: false
worlds:
  world:
    x: 0.0
    z: 0.0
    radiusX: 5000
    radiusZ: 5000
    wrapping: false
  world_nether:
    x: 0.0
    z: 0.0
    radiusX: 5000
    radiusZ: 5000
    wrapping: false
  world_the_end:
    x: 0.0
    z: 0.0
    radiusX: 5000
    radiusZ: 5000
    wrapping: false

I'm using PaperMC 1.14.2 with the following plugins: Copy-Coords*, CoreProtect, CustomMOTD*, DiscordSRV, LuckPerms, ViaVersion*, WorldBorder
Server version: "This server is running Paper version git-Paper-55 (MC: 1.14.2) (Implementing API version 1.14.2-R0.1-SNAPSHOT)"

It looks like they finally fixed it:
https://hub.spigotmc.org/jira/browse/SPIGOT-5252

So it should hopefully be handled in the next Spigot release.

I'm getting this same issue, it seems like it's moving players based on the nether border instead of the overworld border when travelling from nether to overworld.

Same issue here. Not sure if my nether is actually 8 times smaller than the overworld but i am going to trim it just in case. However on the wayback from the nether players get slinghsotted back to the center of the map causing a lot of lag. And they get the out of border message..

Looks like a duplicate of #131.

Yup, same issue here.