• /whois tab-completion isn't working.

• The new playtime is completly wrong. there is a statistics folder in the over-world with the players playtime in this, already waiting, checking on a player with 110 days playtime it says they have played 2 days.

Create issues separately please.

Tab completion fixed in 12930cf. You can grab the fix from build 493 on the CI server.

playtime is based on statistics. Make sure you're not deleting the statistics files.

Awesome. Im not deleting Statistics files, I never have, at what point would I be deleting statistic files?

Statistics files exist in the main world directory. So any playtime that is displayed on there is what Minecraft thinks.

Do you have a multiworld inventory/player data plugin installed like PerWorldInventories, MultiInv or Multiverse-Inventories? They might be configured to overwrite player data when switching worlds.

@md678685 nope.