2023-04-16T21:01:00 1238.241 WRN Spawned entity with wrong pos: [type=EntityPlayer, name=pocket951♥, id=100289] id=100289 pos=(0.0, 0.0, 0.0)
Player profile corrupted. Maybe because of the stupid symbol in the name. Maybe for a number of other reasons. Most common is dying, not respawning, and the server/host shutting down. Second most common is alt-F4 exiting the client because you want to cheat death or something. Non-standard characters in names have been known to cause issues as well in the past. Tell them not to get so creative and just use normal alphabet characters.
When they are joining, but before they are loaded, try teleporting them to valid coordinates. If that doesn't fix it, then nuke the player data and gift them exp/gear.