What i did / Steps to reproduce

1. Installation:
   Install plugin from https://hangar.papermc.io/Blue/BlueMap
2. Configuration
   Accept the whatever in the config, no extra modification

Into freecam mode

Issue

https://sightsee.teamfuho.net/#world:1682:10:-790:0:-0.45:1.52:0:0:free

Context

[06:40:37 INFO]: §fThis server is running Purpur version git-Purpur-1171 (MC: 1.16.5) (Implementing API version 1.16.5-R0.1-SNAPSHOT)§r
[06:39:16 INFO]: Version: 3.14
[06:39:16 INFO]: Commit: 16b1300ced39d7b76938599e00790d708b8e0cb1
[06:39:16 INFO]: Implementation: bukkit
[06:39:16 INFO]: Minecraft compatibility: 1.16.5 (1.16.2)
[06:39:16 INFO]: Render-threads: 1
[06:39:16 INFO]: Available processors: 2
[06:39:16 INFO]: Available memory: 2136 MiB

Networking:

• Reverse proxied through caddy
• 

BlueMap decided that the corner was too dark and therefore a cave. Expected default behaviour. You can configure this to your liking, here's some explanation about how: https://bluemap.bluecolored.de/community/CaveRendering.html

Not a bug, a feature :D
Bluemap thinks those dark spots are caves.
You will need to turn on/fine tune cave-rendering to see those dark spots :)

Read more about this here: https://bluemap.bluecolored.de/community/CaveRendering.html

If you need support with this, feel free to join our discord :)