One fix, from a live server report.

The plugin now notices when another plugin overwrites it

If something else on the server also writes view or simulation distance, the plugin never knew. Every cycle it read the foreign value as the current state, wrote its own over it, logged an honest change, and did the same thing again 30 seconds later.

On the server this was reported from, that meant twenty worlds producing the same log line every 30 seconds, forever, and players reloading chunks on a timer because the value kept moving. Nothing in the log suggested the plugin was being overruled rather than simply doing its job, so finding the cause took hours. It turned out to be a lag-management plugin with its own view distance feature.

The plugin now remembers what it last set. If a world comes back changed three checks in a row, it says so once:

'world_nether': view distance set to 12 but found at 20 on the next check, 3 times in
a row. Something else on this server writes these values too ... Leaving this
world alone. Check your other plugins for a view-distance setting, then
/vdt reload to resume managing it.

Then it stops managing that world, which ends both the log spam and the chunk reloading. /vdt status marks the world so the state is visible after the warning has scrolled away. A reload, or setting that world by hand, resumes management.

Three checks rather than one on purpose: a single mismatch is an admin running a command or a world reloading, not a second plugin.

Upgrading

No config changes and no new keys. Replace the jar and restart.