In order to spectate inventories of offline players, InvSee++ needs to do UUID lookups when the provided argument in the command is a username.
The order in which the strategies to look up UUIDs are attempted is changed in this update. The order is now as follows:

1. Get it from the player in case they are online.
2. If step 1 didn't succeed, get it from the cache of recenly logged out players.
3. If step 2 didn't succeed, get it from the offline player cache in Paper-api enabled servers.
4. If step 3 didn't succeed, get it from the permission plugin (supports LuckPerms, GroupManager, BungeePerms and UltraPermissions).
5. If step 4 didn't succeed, get it from the proxy server using plugin messages (supports BungeeCord and Velocity).
6. If step 5 didn't succeed, get it by making a REST api call to Mojang.
7. If step 6 didn't succeed, get it from the player save files directly.

The last two strategies have been swapped, so that on server with lots of players getting the UUID won't take as long anymore since it's very likely that the player save files don't have to be inspected anymore.
Strategies 3 and 4 are also new in this update.