i did not have this issue in the past. i use vanilla server.jar with spawn monsters false in properties file and i updated game and launched server and logeed in and then monsters were spawned in overworld like skeleton and zombie and spider. please check it. other monsters was not checked out.
steps to reproduce
set server
set properties file with settings like spawn monsters false
login into server from game
wait or set night then monsters appear
Environment
temurin with jdk 21.0.7+6
The
spawn-monsters
server property does not exist anymore. Monster spawning is now controlled by thespawnMonsters
game rule. This is not a bug.